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There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

There's a couple ways to generate one-time pads. The first I read was described at HotBits. They take a little radioactive bit of cesium, and a radiation detector which can detect atomic decay:

What we do, then, is measure a pair of these intervals, and emit a zero or one bit based on the relative length of the two intervals. If we measure the same interval for the two decays, we discard the measurement and try again, to avoid the risk of inducing bias due to the resolution of our clock.

You can find more at Wikipedia's article on hardware random number generators:

There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)

Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:

• Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.

• A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.

• Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique SA. The mutually exclusive events (reflection -- transmission) are detected and associated to "0" or "1" bit values respectively.

Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:

• thermal noise from a resistor, amplified to provide a random voltage source.

• Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.

Strictly speaking the Stern-Gerlach experiment: passing a beam of electrons through a magnetic field and detecting the two resulting beams, doesn't flip the spin it sorts electrons based on their spin.

Controlling the spin of electrons is hard, if you work with an electron beam, perhaps one you filtered to contain only one spin orientation, you have to insulate the beam from the environment to make sure the spins don't interact and change orientation later on. Furthermore the electrons within the beam themselves will interact and a beam of purely one spin state will eventually contain both spin states unless you put energy in the system to keep your spin state energetically favorable, usually by passing the beam through a constant magnetic field, but that will deflect the beam since electrons are charged and that puts limits on how far the beam can travel before it hits something or intersects itself.

Working with electrons bound to atoms is a little easier, you don't have to worry about maintaining a magnetic field along the path of a beam since the electrons aren't going anywhere. On the other hand in a bulk material to have electrons which are free to change spin state they have to be unpaired and atoms or molecules with unpaired spins tend to be highly reactive. Thus they will tend to combine with other atoms or molecules to form combinations whose spin cannot be measured.

This leads to the most common technique of spin manipulation which controls the spins of atomic nuclei in bulk material. Because the electrons shield the nuclei they tend to remain in one spin state for a little while, in fact because the local environment of each nucleus in a bulk material is determined by the combination of a known external magnetic field and the local electron environment you can get information about molecular structure from NMR. To be precise though magnetic resonance techniques both electron and nuclear depend on the fact that in an external magnetic field there will be a slight population difference in spin states for a bulk material. The individual spins will still transition between states due to interactions with the environment but you can hold a large enough number of them in a particular state for long enough to be able to manipulate spins in the desired state for a little while before they decohere.

So to answer your question, the cheapest practical spin manipulation device is an NMR spectrometer. I'm having locating one for sale for cheap, there used to be a couple of companies selling 60MHz and tabletop permanent magnet NMRs for educational use but I can't find any of them now. You can build one yourself for on the order of $2,000, all you need is time, some soldering skills, a permanent magnet in a solenoid configuration, an oscilloscope which is probably the most expensive part, and a circuit diagram for 60MHz oscillator. Or you can use software to simulate NMR experiments.

The holy grail of spin manipulation of course is to trap and manipulate a single atom or molecule, or a small ensemble of such in an entangled state, which is of course what the research article reference above is about.