According to the news from the University of Science and Technology of China, a research team led by Pan Jianwei, Lu Chaoyang, Chen Mingcheng, etc., has for the first time fully realized the "recoiling slit" quantum interference thought experiment proposed by Einstein and Bohr in 1927, using quantum ground-state single atoms trapped by optical tweezers. They observed the gradual change process of tunable atomic momentum interference contrast, proved the complementarity principle under the Heisenberg limit, and demonstrated the continuous transition from quantum to classical. The related results were published on December 3 in the international academic journal "Physical Review Letters".
At the fifth Solvay Conference, Einstein challenged Bohr's complementarity principle by designing a double-slit interference experiment with a movable slit. Einstein believed that a single photon would impart an extremely weak recoil momentum to the slit. If this recoil could be measured, the path of the photon could be determined, while if the slit position was precise enough, the interference fringes could still be retained. This thought experiment is regarded as one of the deepest paradoxes in quantum mechanics.
The key to realizing this thought experiment lies in measuring the effective recoil signal, which requires the momentum uncertainty of the slit to be less than the momentum of the photon. However, due to the very weak momentum recoil of a single photon, much smaller than the momentum uncertainty of macroscopic objects, this ingenious thought experiment remained at the level of "thought" for nearly a century.
It is reported that in this research work, the research team achieved the most sensitive "movable slit" under quantum limit conditions: using a single rubidium atom trapped by optical tweezers as the "movable slit", and preparing the atom into a three-dimensional motion ground state through Raman sideband cooling technology, reducing its momentum uncertainty to a level comparable to that of a single photon. At the same time, the experiment can flexibly adjust the depth of the optical tweezers trapping potential to change the momentum uncertainty of the atomic slit.
The experimental results show that after the photon recoil, the overlap of the atomic momentum wave function increases, leading to a decrease in the entanglement between the photon and the atom, thereby increasing the photon interference contrast. In addition, the observed decrease in interference contrast in the experiment is partly caused by atomic heating. After calibrating and removing the influence of this classical noise, the experimental data highly coincided with the photon interference contrast when the atom was in a perfect ground state.
The researchers stated that this study, nearly a century after Einstein and Bohr's debate on the foundation of quantum mechanics, is the first time that a ground-state single atom has been used as a "movable slit" sensitive to the momentum of a single photon. It not only realizes Einstein's thought experiment at the quantum limit, but also develops precision quantum technologies such as high-precision single-atom manipulation, single-atom-single-photon entanglement and interference, laying the foundation for future large-scale neutral atom arrays, compressed state error correction coding, and further exploration of decoherence and the quantum-to-classical transition.
Source: China Economic Net
Original: toutiao.com/article/7579990296788877878/
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