【悲報？朗報？】【研究】量子コンピュータを使って「時間を逆転させる」実験に成功／モスクワ物理工科大学

1 ：以下、？ちゃんねるからVIPがお送りします：2019/03/15(金) 16:41:40.131 ID:Z45Qq0c+0.net

モスクワ物理学研究所の研究者は、米国とスイスの同僚と協力して、量子コンピュータの状態を1秒の何分の1か過去に戻しました。
彼らはまた、星間空間にある電子が自発的に短い過去に戻る確率を計算しました。
この研究は3月13日にScientific Reportsに掲載されました。

中略

チームは、短い過去に、自発的に局在化するほんの一瞬のうちに電子が「にじむ」ことを観測する確率を計算することに着手しました。
毎秒100億個の新しく局在化した電子を観測して宇宙の全寿命（137億年）を過ごしたとしても、粒子の状態の逆進化は1回しか発生しないことがわかりました。

中略

研究者らは、85％のケースで、2量子ビット量子コンピューターが実際に初期状態に戻ったことを発見しました。3つのキュビットが関係していたとき、より多くのエラーが起こりました。結果としておよそ50パーセントの成功率をもたらしました。
著者によると、これらのエラーは実際の量子コンピュータの不完全性によるものです。より高度な装置が設計されるにつれて、誤り率は低下すると予想されます。

2 ：以下、？ちゃんねるからVIPがお送りします：2019/03/15(金) 16:42:51.813 ID:tsDrsnxf0.net

わかった(わかってない)

3 ：以下、？ちゃんねるからVIPがお送りします：2019/03/15(金) 16:42:59.870 ID:H+r3IvQY0.net

はいはい虚構新聞虚構新聞

4 ：以下、？ちゃんねるからVIPがお送りします：2019/03/15(金) 16:52:43.907 ID:yutq5f2c0.net

https://www.independent.co.uk/life-style/gadgets-and-tech/news/time-reverse-quantum-computer-science-study-moscow-a8820516.html

5 ：以下、？ちゃんねるからVIPがお送りします：2019/03/15(金) 16:54:59.658 ID:Z45Qq0c+0.net

Physicists reverse time using quantum computer
MOSCOW INSTITUTE OF PHYSICS AND TECHNOLOGY

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 comes out March 13 in Scientific Reports.

"This is one in a series of papers on the possibility of violating the second law of thermodynamics. That law is closely related to
the notion of the arrow of time that posits the one-way direction of time: from the past to the future,"
commented the study's lead author Gordey Lesovik, who heads the Laboratory of the Physics of Quantum Information Technology at MIPT.

"We began by describing a so-called local perpetual motion machine of the second kind. Then, in December, we
published a paper that discusses the violation of the second law via a device called
a Maxwell's demon," Lesovik said. "The most recent paper approaches the same problem from a third angle: We have artificially created a state
that evolves in a direction opposite
to that of the thermodynamic arrow of time."

What makes the future different from the past

Most laws of physics make no distinction between the future and the past. For example,
let an equation describe the collision and rebound of two identical billiard balls. If a close-up of that event is recorded with a camera and played in reverse,
it can still be represented by the same equation.
Moreover, one could not tell from the recording if it has been doctored. Both versions look plausible. It would appear that the billiard balls
defy the intuitive sense of time.

However, imagine that someone has recorded a cue ball breaking the pyramid, the billiard balls
scattering in all directions. One need not know the rules of the game to tell the real-life scenario from reverse playback. What makes the latter
look so absurd is our intuitive understanding of the second law of thermodynamics: An isolated system either remains static or evolves toward a state of chaos rather than order.

Most other laws of physics do not prevent rolling billiard balls from assembling into a pyramid, infused tea from flowing back into the
tea bag, or a volcano from "erupting" in reverse. But we do not see any of this happening, because that would require an
isolated system to assume a more ordered state without any outside intervention, which runs contrary to the second law. The nature of that law has not been
explained in full detail, but researchers have made great headway in understanding the basic principles behind it.

Spontaneous time reversal

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.

※続きは下記のソースでご覧ください

https://www.eurekalert.org/pub_releases/2019-03/miop-prt031119.php
https://www.independent.co.uk/life-style/gadgets-and-tech/news/time-reverse-quantum-computer-science-study-moscow-a8820516.html
https://arxiv.org/pdf/1712.10057.pdf