Abstract Quantum memories are essential for quantum information processing. Techniques have been developed for quantum memory based on atomic ensembles. The atomic memories through optical resonance usually suffer from the narrow-band limitation. The far off-resonant Raman process is a promising candidate for atomic memories due to broad bandwidths and high speeds. However, to date, the low memory efficiency remains an unsolved bottleneck. Here, we demonstrate a high-performance atomic Raman memory in 87 Rb vapour with the development of an optimal control technique. A memory efficiency of above 82.0% for 6 ns~20 ns optical pulses is achieved. In particular, an unconditional fidelity of up to 98.0%, significantly exceeding the no-cloning limit, is obtained with the tomography reconstruction for a single-photon level coherent input. Our work marks an important advance of atomic memory towards practical applications in quantum information processing.Abstract Quantum memories are essential for quantum information processing. Techniques have been developed for quantum memory based on atomic ensembles. The atomic memories through optical resonance usually suffer from the narrow-band limitation. The far off-resonant Raman process is a promising candidate for atomic memories due to broad bandwidths and high speeds. However, to date, the low memory efficiency remains an unsolved bottleneck. Here, we demonstrate a high-performance atomic Raman memory in 87 Rb vapour with the development of an optimal control technique. A memory efficiency of above 82.0% for 6 ns~20 ns optical pulses is achieved. In particular, an unconditional fidelity of up to 98.0%, significantly exceeding the no-cloning limit, is obtained with the tomography reconstruction for a single-photon level coherent input. Our work marks an important advance of atomic memory towards practical applications in quantum information processing.

arXiv:1804.10763Nature CommunicationsJan 8, 2019128 citations

Quantum Memory in Atomic Ensembles

Joshua Nunn

Jan 1, 200810 citations

Broad spiral bandwidth of orbital angular momentum interface between photon and memory

Dong-Sheng Ding, Ming‐Xin Dong, Wei Zhang +5 more

Abstract The complex interactions between orbital angular momentum (OAM) of light and atoms are particularly intriguing in the areas of quantum optics and quantum information. Building a versatile high-dimensional quantum network needs broad spiral-bandwidth for preparing higher-quanta OAM mode and resolving the bandwidth mismatch in spatial space. Here, we demonstrate a broad spiral-bandwidth quantum-interface between photon and memory. Through twisted fields of the writing and reading, the correlated OAM distribution between photon and memory is significantly broadened. This broad spiral-bandwidth quantum-interface could be spanned in multiplexing regime and could work in high-quanta scenario with capability of $\vert l\vert =$ ∣ l ∣ = 30, and we demonstrate the entanglement within 2-D subspace with a fidelity of 80.5 ± 4.8% for high $l$ l . Such state-of-the-art technology to freely control the spatial distribution of OAM memory is very helpful to construct high-dimensional quantum networks and provides a benchmark in the field of actively developing methods to engineer OAM single photon from matters.Abstract The complex interactions between orbital angular momentum (OAM) of light and atoms are particularly intriguing in the areas of quantum optics and quantum information. Building a versatile high-dimensional quantum network needs broad spiral-bandwidth for preparing higher-quanta OAM mode and resolving the bandwidth mismatch in spatial space. Here, we demonstrate a broad spiral-bandwidth quantum-interface between photon and memory. Through twisted fields of the writing and reading, the correlated OAM distribution between photon and memory is significantly broadened. This broad spiral-bandwidth quantum-interface could be spanned in multiplexing regime and could work in high-quanta scenario with capability of $$\vert l\vert =$$ ∣ l ∣ = 30, and we demonstrate the entanglement within 2-D subspace with a fidelity of 80.5 ± 4.8% for high $$l$$ l . Such state-of-the-art technology to freely control the spatial distribution of OAM memory is very helpful to construct high-dimensional quantum networks and provides a benchmark in the field of actively developing methods to engineer OAM single photon from matters.

arXiv:1806.10407Communications PhysicsAug 28, 201912 citations

Broadband quantum memory in atomic ensembles

Kai Shinbrough, Donny R. Pearson, Bin Fang +2 more

arXiv:2301.08772Advances in atomic, molecular, and optical physicsJan 1, 20239 citations

Three-dimensional theory of quantum memories based on Λ -type atomic ensembles

Emil Zeuthen, Anna Grodecka-Grad, Anders Søndberg Sørensen

We develop a three-dimensional theory for quantum memories based on light storage in ensembles of $\ensuremath{\Lambda}$-type atoms, where two long-lived atomic ground states are employed. We consider light storage in an ensemble of finite spatial extent and we show that within the paraxial approximation the Fresnel number of the atomic ensemble and the optical depth are the only important physical parameters determining the quality of the quantum memory. We analyze the influence of these parameters on the storage of light followed by either forward or backward read-out from the quantum memory. We show that for small Fresnel numbers the forward memory provides higher efficiencies, whereas for large Fresnel numbers the backward memory is advantageous. The optimal light modes to store in the memory are presented together with the corresponding spin waves and outcoming light modes. We show that for high optical depths such $\ensuremath{\Lambda}$-type atomic ensembles allow for highly efficient backward and forward memories even for small Fresnel numbers $F\ensuremath{\gtrsim}0.1$.We develop a three-dimensional theory for quantum memories based on light storage in ensembles of $\ensuremath{\Lambda}$-type atoms, where two long-lived atomic ground states are employed. We consider light storage in an ensemble of finite spatial extent and we show that within the paraxial approximation the Fresnel number of the atomic ensemble and the optical depth are the only important physical parameters determining the quality of the quantum memory. We analyze the influence of these parameters on the storage of light followed by either forward or backward read-out from the quantum memory. We show that for small Fresnel numbers the forward memory provides higher efficiencies, whereas for large Fresnel numbers the backward memory is advantageous. The optimal light modes to store in the memory are presented together with the corresponding spin waves and outcoming light modes. We show that for high optical depths such $\ensuremath{\Lambda}$-type atomic ensembles allow for highly efficient backward and forward memories even for small Fresnel numbers $F\ensuremath{\gtrsim}0.1$.

arXiv:1105.2662Physical Review AOct 24, 201122 citations

Further Improvement of Atomic Ensemble Quantum Memories

Yong Hui Yu

Springer thesesJan 1, 20230 citations

\vert l\vert =

∣ l ∣ = 30, and we demonstrate the entanglement within 2-D subspace with a fidelity of 80.5 ± 4.8% for high

l

l . Such state-of-the-art technology to freely control the spatial distribution of OAM memory is very helpful to construct high-dimensional quantum networks and provides a benchmark in the field of actively developing methods to engineer OAM single photon from matters.