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Quantum nonlocality at all velocities (via Qpute.com)

The new results prove that it is possible to design a Belle experiment of particles that move in quantum superposition at very high speeds. Credit: ALOOP; ÖAW

The phenomenon of quantum nonlocality goes against our daily intuition. It shows a strong correlation between some quantum particles, some of which change state instantly when other quantum particles are measured, regardless of the distance between them. This phenomenon has been confirmed for slow-moving particles, but nonlocality is maintained when the particles move very fast at speeds close to the speed of light, and when their velocities are quantum-mechanically indefinite. Whether or not is being discussed. Researchers at the University of Vienna, the Austrian Academy of Sciences, and the Perimeter Institute are currently reporting in their latest issue. Physical review letter Its nonlocality is a universal property of the world, regardless of how or at what speed quantum particles move.

It’s easy to explain how correlations occur in everyday life. Imagine sending two of your friends, Alice and Bob, together each month with a pair of toy engines. Each engine can be red or blue, or electric or steam. Your friends are far away and don’t know about your choice. When your luggage arrives, you can use a device that can distinguish between red and blue to see the color of the engine, or another device to see if the engine is electric or steam. They compare measurements taken over time to look for specific correlations. In our everyday world, such correlations follow two principles: “realism” and “locality”. “Realism” means revealing only the engine color or mechanism that Alice and Bob have selected in the past, and “locality” means that Alice’s measurements cannot change the color or mechanism of Bob’s engine. That means (or vice versa). Bell’s theorem, published in 1964 and considered to be one of the most profound discoveries in the foundations of physics, states that the correlation of the quantum world is two principles (a phenomenon known as quantum nonlocality). Showed that they are incompatible.

Quantum nonlocality has been confirmed in many experiments on atoms, ions, and electrons, the so-called Bell experiment. Not only does it have a deep philosophical meaning, it also underpins many applications such as quantum computing and quantum satellite communications. However, in all these experiments, the particles were stationary or moving slowly (scientists call this regime “non-relativistic”). One of the unsolved problems in this area that still puzzles physicists is that the particles are very fast, Speed ​​of light (Ie, in a relativistic regime), or when they are not moving even at a well-defined speed.

For two people Quantum particles In the bell experiment high speed, Researchers predict that the correlation between particles will decrease in principle. However, if Alice and Bob adapt the measurements in a way that depends on the velocity of the particles, the correlation between the measurements remains nonlocal. Now imagine that not only do the particles move very fast, but their speed is also indefinite. Just as the infamous Schrodinger cat is dead and alive at the same time, each particle moves at the same time at different velocities, so-called superpositions. In such cases, aren’t their depictions of the world still local?

Researchers led by Časlav Brukner of the University of Vienna and the Austrian Academy of Sciences have shown that Alice and Bob can actually design experiments that prove that the world is nonlocal. For this, they used one of the most basic principles of physics. In other words, the physical phenomenon does not depend on the frame of reference we observe. For example, according to this principle, an observer will see an apple fallen from a tree touching the ground, whether moving or not. Researchers went one step further and extended this principle to refer to frames that “attached” to quantum particles. These are called “quantum reference frames”. An important insight is that if Alice and Bob can move with their respective particles along with the quantum reference frame, then the particles are stationary and the normal Bell experiment can be performed. In this way, we can prove the quantum nonlocality of any quantum particle, regardless of whether the velocity is indefinite or close to the speed of light.

“Our results prove that it is possible to design a Belle experiment of particles moving in quantum superposition at very high speeds,” said Flaminia Giacomini, one of the authors of the study. I will. Co-author Lucas Streiter concludes, “Nonlocality has shown to be a universal property of our world.” Their discoveries are expected to open up applications in quantum technologies such as quantum satellite communications and quantum computation using relativistic particles.

For more information:
Lucas F. Streiter et al, Relativistic Bell Experiment in Quantum Reference Frame, Physical review letter (2021). DOI: 10.1103 / PhysRevLett.126.230403

Quote: Quantum nonlocality at all velocities (2021, June 16) was obtained from https://phys.org/news/2021-06-quantum-nonlocality.html on June 16, 2021. Ta

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