Backward retrieval in optical quantum memory controlled by an external field

在斯图尔特调制的自旋波量子存储器中实现反向检索

Realization of Backward Retrieval in a Stark-modulated Spin-wave Quantum Memory

该研究通过斯图尔特回声调制协议在Eu3+:Y2SiO5中实现了反向检索的首次实验验证，展示了高保真度的存储与高效检索，证明技术限制是主要瓶颈，为高效率固态量子存储提供新途径。

Quantum memories with electrically controlled storage and retrieval in an opto- and electro-mechanical cavity

We propose a novel scheme to realize electrically controlled quantum memories in the opto- and electro-mechanical (OEM) cavity. Combining this OEM cavity with the mechanism of Electromagnetically Induced Transparency (EIT) we find that the quantum interference, arising from the two optical transitions of the $Λ$ type three-level atomic ensembles, can be manipulated electrically. Numerical calculations show that the probe photon state can be well stored into the atomic spin state by sending an electric current pulse and retrieved with time-reverse symmetry by sending the other current pulse wit…

Controlled insertion and retrieval of atoms coupled to a high-finesse optical resonator

We experimentally investigate the interaction between one and two atoms and the field of a high-finesse optical resonator. Laser-cooled caesium atoms are transported into the cavity using an optical dipole trap. We monitor the interaction dynamics of a single atom strongly coupled to the resonator mode for several hundred milliseconds by observing the cavity transmission. Moreover, we investigate the position-dependent coupling of one and two atoms by shuttling them through the cavity mode. We demonstrate an alternative method, which suppresses heating effects, to analyze the atom-field intera…

How much is a quantum controller controlled by the controlled system?

We consider unitary transformations on a bipartite system A x B. To what extent entails the ability to transmit information from A to B the ability to transfer information in the converse direction? We prove a dimension-dependent lower bound on the classical channel capacity C(A<--B) in terms of the capacity C(A-->B) for the case that the bipartite unitary operation consists of controlled local unitaries on B conditioned on basis states on A. This can be interpreted as a statement on the strength of the inevitable backaction of a quantum system on its controller. If the local operations are gi…

无需受控幺正的量子相位估计

Quantum Phase Estimation without Controlled Unitaries

本研究提出两种基于经典相位恢复算法的无受控幺正量子相位估计方法，降低线路深度以适配近期量子设备，数值验证了其在Fermi-Hubbard模型光谱估计中的可行性及抗统计噪声能力。

High-performance Raman memory with spatio-temporal reversal

A number of techniques exist to use an ensemble of atoms as a quantum memory for light. Many of these propose to use backward retrieval as a way to improve the storage and recall efficiency. We report on a demonstration of an off-resonant Raman memory that uses backward retrieval to achieve an efficiency of $65\pm6\%$ at a storage time of one pulse duration. The memory has a characteristic decay time of 60 $μ$s, corresponding to a delay-bandwidth product of $160$.