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Physicists set a new record of quantum memory efficiency



  HKUST physicist contributes to a new record of quantum memory efficiency
Experimental setup and energy level of single-photon quantum memory. Credit: Hong Kong University of Science and Technology

As a memory in conventional computers, quantum memory components are crucial for quantum computers ̵

1; a new generation of data processors that utilize quantum mechanics and can overcome the limitations of classical computers. With their powerful computing power, quantum computers can push the boundaries of basic science to create new drugs, explain cosmological mysteries, or increase the accuracy of forecasts and optimization plans. Quantum computers are expected to be much faster and more powerful than their traditional counterparts, since information is calculated in qubits, which, unlike the bits used in classic computers, can represent both zero and one in a simultaneous superstate.


Photon quantum memory allows the storage and retrieval of flying single-photon quantum states. However, the production of such a high efficient quantum memory remains a major challenge as it requires a perfectly matched photon material quantum interface. Meanwhile, the energy of a single photon is too weak and can easily be lost in the noisy sea of ​​dim light. For a long time, these problems have suppressed quantity memory efficiency to less than 50 percent – a threshold value for practical applications.

Now for the first time, a joint research team led by Prof. Du Shengwang from HKUST, Prof. Zhang Shanchao from SCNU, Prof. Yan Hui from SCNU and Prof. Zhu Shi-Liang from SCNU and Nanjing University have found a way to Increase the efficiency of photonic quantum memory to over 85 percent with a credibility of over 99 percent.

The team created such quantum memory by capturing billions of rubidium atoms in a small hair-like space – these atoms are cooled to almost absolute zero (about 0.001001 K) by lasers and a magnetic field. The team also found a smart way to distinguish a single photon from the noisy backlight. The result brings the dream of a universal quantum computer a step closer to reality. Such quantum memory devices can also be implemented as a repeater in a quantum network that forms the basis of a new generation of quantum-based internet.

"In this work we coded a flying qubit on the polarization of a single photon and shop it in the laser-cooled atoms," said prof you. "Although the quantum memory demonstrated in this work is only for a qubit operation, it opens the possibility of future quantum technology and technology in the future."

The result was recently published as a cover story of the authoritative journal Nature Photonics the latest of a series of research by Prof Du & # 39; s quantum memory lab that first began in 2011.


Physicists get thousands of semiconductor cores to do quantum dances & # 39; in harmony


More information:
Yunfei Wang et al., Effective quantum memory for single-photon polarization qubits, Nature Photonics (2019). DOI: 10,1038 / s41566-019-0368-8

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Hong Kong University of Science and Technology

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Physicists set a new record of quantum memory efficiency (2019, April 29)
April 29, 2019
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