Previously, scientists have only observed quantum entanglement in the microscopic world – a magical state in which two particles are synchronized across space. Recently, physicists have also observed this phenomenon at the macroscopic scale and found that it breaks the classical uncertainty principle in quantum science (also translated as the unpredictability principle).
The study used two small aluminum drums of only about 10 microns, and used microwave photons to make their drums vibrate, keeping their positions and velocities in sync. Such a scale is only one-fifth of the diameter of a human hair, which is still very small for the world visible to the human eye, but for the microscopic world controlled by quantum physics, it is already a huge object.
Macroscale quantum entanglement also follows microscopic laws
Particles in a state of quantum entanglement exhibit properties that cannot be explained by classical physical theory and have important uses in many fields. Scientists previously thought that if it occurred in the macroscopic world, the physical properties of this phenomenon might not be the same as at the microscopic level.
This study finds that this is not the case. In fact, the large scale quantum entanglement seen in this study follows the same quantum laws as in the microscopic world.
While macroscopic quantum entanglement has been reported in previous studies, this new study is a significant advance: for the first time, it is possible to measure an entangled object rather than speculate to get an estimate; and it produces the entangled state of the object with a high degree of certainty, without random chance.
Because quantum states are easily disturbed by external factors, the researchers cooled the snare drums to a low temperature of about minus 273 degrees Celsius to avoid disturbances. The states of the two snare drums are encoded into a radar-like reflected microwave field that can be measured separately.
Breaking the quantum inaccuracy principle
The most interesting aspect of this research is that it bypasses the uncertainty principle proposed by German physicist Werner Heisenberg. According to Heisenberg, in quantum mechanics, the position and momentum of a particle cannot be measured at the same time, or the measurement of one side will interfere with the other side, also called quantum back action.
This study bypasses the quantum back action and is able to measure the position and kinetic energy of two snare drums at the same time.
Laure Mercier de Lepinay, a physicist at Aalto University in Finland, one of the lead researchers, said, “In our study, the two snare drums exhibit a cooperative quantum state of motion, vibrating in opposite phases, such that one of them is located at the end of the vibration The two snare drums in our study exhibit a cooperative quantum state of motion in which they vibrate in opposite phases, such that one is located at the end of the cycle, while at the same time the other is located at the beginning. In such a case, if the two snare drums are considered as one quantum mechanical entity, then the quantum uncertainty in the motion of the snare drum is cancelled out.”
The study says the experiment is a fundamental insight into the boundary between classical physics (not controlled by the uncertainty principle) and quantum physics (controlled by the uncertainty principle).
The researchers hope the results lay the groundwork for the future ability to entangle two objects, and control them, at the macroscopic scale. Macroscopic entanglement has important uses in quantum networks and will drive the development of next-generation communication networks.
The study was published May 7 in the journal Science.
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