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IBM Scientists Measure the Heat Emitted From Erasing a Single Bit

Posted by timothy on from the part-of-a-healthy-weight-loss-program dept.

ananyo writes "In 1961, IBM physicist Rolf Landauer argued that to reset one bit of information — say, to set a binary digit to zero in a computer memory regardless of whether it is initially 1 or 0 — must release a certain minimum amount of heat, proportional to the ambient temperature. New work has now finally confirmed that Landauer was right. To test the principle, the researchers created a simple two-state bit: a single microscopic silica bead held in a 'light trap' by a laser beam. (Abstract) The trap contains two 'valleys' where the particle can rest, one representing a 1 and the other a 0. It could jump between the two if the energy 'hill' separating them is not too high. The researchers could control this height by changing the power of the laser, and could 'tilt' the two valleys to tip the bead into one of them by moving the physical cell containing the bead slightly out of the laser's focus. By monitoring the position and speed of the particle during a cycle of switching and resetting the bit, they could calculate how much energy was dissipated."

3 of 111 comments (clear)

  1. Re:Spirit by Ihmhi · · Score: 4, Interesting

    Yeah, it's kind of like a piece of armor being considered arrow-proof, and then you fire an arrow out of a railgun.

    I wonder how you would even measure it, though, and distinguish the heat from a bit changing from the ambient heat from drive operation.

    --
    Random Thoughts From A Diseased Mind (Not For Dummies)
  2. Re:Yes, it's the entropy by Anonymous Coward · · Score: 5, Interesting

    Specifically in the calculation of the Landauer limit, E = kT(ln2), the minimal energy needed to transform a single bit. The interesting thing is that 10^20 bit operations is just a watt. This means that the efficiency of today's computers is just 0.00001%. More details at http://tikalon.com/blog/blog.php?article=2011/Landauer.

  3. What if I store bits as heat? by Anonymous Coward · · Score: 1, Interesting

    Let 0s be room temperature and let 1s be somewhat below room temperature. Then to erase the memory I expose it to the room. As it erases the memory will absorb some heat from the room instead of releasing heat.

    Not really a practical form of computer memory, but seems sufficient to disprove Landauer.