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Physicists Reverse Time Using Quantum Computer (phys.org)
fahrbot-bot shares a report from Phys.Org: Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past. They also calculated the probability that an electron in empty interstellar space will spontaneously travel back into its recent past. The study is published in Scientific Reports.
Quantum physicists from MIPT decided to check if time could spontaneously reverse itself at least for an individual particle and for a tiny fraction of a second. That is, instead of colliding billiard balls, they examined a solitary electron in empty interstellar space. "Suppose the electron is localized when we begin observing it. This means that we're pretty sure about its position in space. The laws of quantum mechanics prevent us from knowing it with absolute precision, but we can outline a small region where the electron is localized," says study co-author Andrey Lebedev from MIPT and ETH Zurich. The physicist explains that the evolution of the electron state is governed by Schrodinger's equation. Although it makes no distinction between the future and the past, the region of space containing the electron will spread out very quickly. That is, the system tends to become more chaotic. The uncertainty of the electron's position is growing. This is analogous to the increasing disorder in a large-scale system -- such as a billiard table -- due to the second law of thermodynamics.
"However, Schrodinger's equation is reversible," adds Valerii Vinokur, a co-author of the paper, from the Argonne National Laboratory, U.S. "Mathematically, it means that under a certain transformation called complex conjugation, the equation will describe a 'smeared' electron localizing back into a small region of space over the same time period." Although this phenomenon is not observed in nature, it could theoretically happen due to a random fluctuation in the cosmic microwave background permeating the universe. The team set out to calculate the probability to observe an electron "smeared out" over a fraction of a second spontaneously localizing into its recent past. It turned out that even across the entire lifetime of the universe -- 13.7 billion years -- observing 10 billion freshly localized electrons every second, the reverse evolution of the particle's state would only happen once. And even then, the electron would travel no more than a mere one ten-billionth of a second into the past. The researchers then attempted to reverse time in a four-stage experiment by observing the state of a quantum computer made of superconducting qubits, instead of an electron. The researchers "found that in 85 percent of the cases, the two-qubit quantum computer returned back into the initial state," reports Phys.Org. "When three qubits were involved, more errors happened, resulting in a roughly 50 percent success rate. According to the authors, these errors are due to imperfections in the actual quantum computer. As more sophisticated devices are designed, the error rate is expected to drop."
Quantum physicists from MIPT decided to check if time could spontaneously reverse itself at least for an individual particle and for a tiny fraction of a second. That is, instead of colliding billiard balls, they examined a solitary electron in empty interstellar space. "Suppose the electron is localized when we begin observing it. This means that we're pretty sure about its position in space. The laws of quantum mechanics prevent us from knowing it with absolute precision, but we can outline a small region where the electron is localized," says study co-author Andrey Lebedev from MIPT and ETH Zurich. The physicist explains that the evolution of the electron state is governed by Schrodinger's equation. Although it makes no distinction between the future and the past, the region of space containing the electron will spread out very quickly. That is, the system tends to become more chaotic. The uncertainty of the electron's position is growing. This is analogous to the increasing disorder in a large-scale system -- such as a billiard table -- due to the second law of thermodynamics.
"However, Schrodinger's equation is reversible," adds Valerii Vinokur, a co-author of the paper, from the Argonne National Laboratory, U.S. "Mathematically, it means that under a certain transformation called complex conjugation, the equation will describe a 'smeared' electron localizing back into a small region of space over the same time period." Although this phenomenon is not observed in nature, it could theoretically happen due to a random fluctuation in the cosmic microwave background permeating the universe. The team set out to calculate the probability to observe an electron "smeared out" over a fraction of a second spontaneously localizing into its recent past. It turned out that even across the entire lifetime of the universe -- 13.7 billion years -- observing 10 billion freshly localized electrons every second, the reverse evolution of the particle's state would only happen once. And even then, the electron would travel no more than a mere one ten-billionth of a second into the past. The researchers then attempted to reverse time in a four-stage experiment by observing the state of a quantum computer made of superconducting qubits, instead of an electron. The researchers "found that in 85 percent of the cases, the two-qubit quantum computer returned back into the initial state," reports Phys.Org. "When three qubits were involved, more errors happened, resulting in a roughly 50 percent success rate. According to the authors, these errors are due to imperfections in the actual quantum computer. As more sophisticated devices are designed, the error rate is expected to drop."
This doesn't prove time reversal, it show a quantum computer can unreliably implement the Undo-Redo pattern.
Somebody tell Cher!
Do you actually store shit in the fridge? If so, why? Does it reduce the smell or something?
Yes and yes. I guess you're no microbiologist.
Seven puppies were harmed during the making of this post.
I'm not sure they reversed entropy either. I thought that wasn't actually possible (much like time travel).
They took an electron and took it from state A to B and back to A. The energy required to go from B to A probably caused a net increase in entropy.
I concur though that it feels an ambitious headline. Does this mean I'm reversing time when I take a piss into the glass I drank out of?
Pragmatheism.
Everything in the universe is made up of stuff that is following the path of least resistance while hurling towards the future in a relentless, never-ending push to maximize the rate of entropy growth.
"His name was James Damore."
The ability to recall a previous state and return to it. I've got an idea, should we call this new invention something like "memory"?
I had read the original article. They did not actually reverse time. What they did was cause events that normally only go one way in time to go the other way: e.g., breaking an egg - one can't cause an egg to re-assemble. Well, they did, so to speak. But it did so in the forward time direction.
Entropy is a rule based on probability.
So there is allways a miniscule chance that entropy spontanuously reverses.
And the smaller the system (for instance a couple of particles) the larger the chance of reversal.
The electron is not moving back in time. It is recreating a past state, but in the present time frame. It is not possible to actually measure backwards time travel without the observer also moving back in time. These are my thoughts on the subject.
The universe will stop, and reverse time causing the everything to collapse into a singularity again. That means as the universe goes backwards, the dead will rise from the grave, humanity will eat excrement, un-chew food, and effectively vomit whole pieces of good. Oh, and you will reverse ageing until your a baby and get sucked up by a vagina.
Fun times.
Life is not for the lazy.
The universe will stop, and reverse time causing the everything to collapse into a singularity again. That means as the universe goes backwards, the dead will rise from the grave, humanity will eat excrement, un-chew food, and effectively vomit whole pieces of good. Oh, and you will reverse ageing until your a baby and get sucked up by a vagina.
Fun times.
This is the plot to "Yug Ylimaf" - the fourth episode of season 11 of Family Guy. This in turn may have been inspired by "Backwards' - the first episode of Red Dwarf.
It always makes me feel like I am time traveling.
This in turn may have been inspired by "Backwards' - the first episode of Red Dwarf.
Well, the first episode of Red Dwarf’s third season, anyway...
#DeleteChrome
I came here to say that phase conjugation is not time reversal but I thought about it some more and there are limited ways you might call it pseudo time reversal.
Phase conjugation of a light wave is old stuff. When you do it reverses the direction a shaped wavefront propagates. Since the argument of a wave function f(k*z-w*t) goes backwards when you change the sign on t it's mathematically the same as making time negative. So the wave goes back to where it came from. Notably if it went through phase distorting media then the distortion is not doubled but actually is undone leaving the wave just as it was on the way out.
However if the media was attenuating the wave is not magically amplified on the way back!
So it's not really sending it back in time. It's just phase reversal or conjugation .
The same thing happens in NMR and things like Rabi frequencies. And photon echos.
The same will be true in QM. All they did was created a photon echo.
Except this is with matter not photons so it's pretty banned cool and you don't need to make it sound cooler by sayin it went backward in time.
Keeping matter coherent enough to phase conjugate us aswesome!!!
But I'll note how you could actually time reverse. That would require making the whole container phase conjugate. If we phase conjugated a photon and an attenuating medium the the photon would be amplified so really time reversed!
Some drink at the fountain of knowledge. Others just gargle.