Chinese quantum satellite used to test basic theory in physics

Source: Xinhua| 2019-09-20 03:16:44|Editor: Mu Xuequan
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WASHINGTON, Sept. 19 (Xinhua) -- An international team led by Chinese scientists used a quantum satellite called Micius to test why quantum mechanics and the general theory of relativity, two bedrocks in modern physics, don't work together.

The study published on Thursday online in the journal Science partially ruled out a hypothesis that the entangled particles would decorrelate from one another as they passed through separate gravitational regions of Earth.

According to Albert Einstein's relativity theory, physical phenomena rely on relationship of motion between the observed and the observer. Certain rules hold true across types of observed objects and those observing, but those rules tend to break down at the quantum level, where subatomic particles behave in strange ways.

The hypothesis called "event formalism," proposed by Timothy Ralph at the University of Queensland, claims that the coherence of two entangled photons will be probabilistically decayed when transmitted through the gravity field of the Earth.

It attempted to present a coherent description of quantum fields as they exist in exotic spacetime, but it has never been tested.

Researchers can examine the relationship with quantum and classical physics using light experiments in China's satellite Quantum Experiments at Space Scale (QUESS) or Micius.

"For the first time in human history, we managed to perform a meaningful quantum optical experiment testing the fundamental physics between quantum theory and gravity," said the paper's co-author Pan Jianwei at the University of Science and Technology of China.

The researchers used the satellite to produce and measure two entangled particles: one particle transmitted on the surface while the other passed through the planet's gravity field toward a satellite 500 kilometers above Earth.

"If we did observe the deviation, it would mean that event formalism is correct, and we must substantially revise our understanding of the interplay between quantum theory and gravity theory," Pan said.

By the experiment, the researchers ruled out the strong version of the hypothesis as they did not see the obvious de-coherence rendered by gravity.

Now, Pan and his team are planning to launch a new satellite that will orbit 20 to 60 times higher than Micius to test a wilder field of gravity strength.

"We ruled out the strong version of event formalism, but a modified model remains an open question," Pan said.