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→Quantum arrow of time
According to the Copenhagen interpretation of quantum mechanics, quantum evolution is governed by the Schrödinger equation, which is time-symmetric, and by wave function collapse, which is time irreversible. As the mechanism of wave function collapse is philosophically obscure, it is not completely clear how this arrow links to the others. Despite the post-measurement state being entirely stochastic in formulations of quantum mechanics, a link to the thermodynamic arrow has been proposed, noting that the second law of thermodynamics amounts to an observation that nature shows a bias for collapsing wave functions into higher entropy states versus lower ones, and the claim that this is merely due to more possible states being high entropy runs afoul of Loschmidt's paradox. According to one physical view of wave function collapse, the theory of quantum decoherence, the quantum arrow of time is a consequence of the thermodynamic arrow of time.
According to the Copenhagen interpretation of quantum mechanics, quantum evolution is governed by the Schrödinger equation, which is time-symmetric, and by wave function collapse, which is time irreversible. As the mechanism of wave function collapse is philosophically obscure, it is not completely clear how this arrow links to the others. Despite the post-measurement state being entirely stochastic in formulations of quantum mechanics, a link to the thermodynamic arrow has been proposed, noting that the second law of thermodynamics amounts to an observation that nature shows a bias for collapsing wave functions into higher entropy states versus lower ones, and the claim that this is merely due to more possible states being high entropy runs afoul of Loschmidt's paradox. According to one physical view of wave function collapse, the theory of quantum decoherence, the quantum arrow of time is a consequence of the thermodynamic arrow of time.
根据哥本哈根诠释的量子力学，量子进化是由时间对称的薛定谔方程和不可逆的波函数崩溃控制的。由于波函数崩塌的机制在哲学上是模糊的，所以我们并不完全清楚这个箭头是如何与其他箭头联系起来的。尽管由量子力学的公式计算得出的状态是完全随机的，但是科学家们已经指出了它与热力学箭头的联系并注意到热力学第二定律相当于一个观测工具，它自然表现出一种倾向，倾向于坍缩波函数到更高的熵状态而不是更低的熵状态，同时他们也声称这仅仅是由于更多的可能状态是高熵状态，但这与洛西米特可逆吊诡相冲突。根据波函数坍缩的一个物理观点---- 量子退相干理论，时间的量子箭头是热力学时间箭头的结果。
In 2019, a team of Russian scientists reported the reversal of the quantum arrow of time on an IBM quantum computer. By observing the state of the quantum computer made of two and later three superconducting qubits, they found that in 85% of the cases, the two-qubit computer returned into the initial state. The state's reversal was made by a special program, similarly to the random microwave background fluctuation in the case of the electron. However, according to the estimations, throughout the age of the universe (13.7 billion years) such a reversal of the electron's state would only happen once, for 0.06 nanoseconds. The scientists' experiment led to the possibility of a quantum algorithm that reverses a given quantum state through complex conjugation.
In 2019, a team of Russian scientists reported the reversal of the quantum arrow of time on an IBM quantum computer. By observing the state of the quantum computer made of two and later three superconducting qubits, they found that in 85% of the cases, the two-qubit computer returned into the initial state. The state's reversal was made by a special program, similarly to the random microwave background fluctuation in the case of the electron. However, according to the estimations, throughout the age of the universe (13.7 billion years) such a reversal of the electron's state would only happen once, for 0.06 nanoseconds. The scientists' experiment led to the possibility of a quantum algorithm that reverses a given quantum state through complex conjugation.
2019年，一组俄罗斯科学家报告了 IBM 量子计算机上时间量子箭头的反转。通过观察由两个或三个超导量子位组成的量子计算机的状态，他们发现在85% 的情况下，两个量子位的计算机返回到初始状态。这种状态的反转是通过一个特殊的程序实现的，类似于电子的随机微波背景起伏。然而，根据估计，在整个宇宙的年龄(137亿年) ，这种电子状态的逆转只会发生一次，持续0.06纳秒。科学家们的实验导致了通过复杂共轭反转给定量子态的量子算法的可能性。
2019年，一组俄罗斯科学家报告了 IBM 量子计算机上时间量子箭头的反转。通过观察由两个或三个超导量子位组成的量子计算机的状态，他们发现在85% 的情况下，两个量子位的计算机返回到初始状态。这种状态的反转是通过一个特殊的程序实现的，类似于电子的随机微波背景起伏。然而，根据测算，在整个宇宙的年龄(137亿年) ，这种电子状态的逆转只会发生一次，持续0.06纳秒。科学家们的实验表明通过复杂共轭反转给定量子态的量子算法是可能的。
=== Quantum source of time ===
=== Quantum source of time ===