High-performance Raman quantum memory with optimal control in room temperature atoms

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 87Rb 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.

Quantum network based on non-classical light

“…Besides, along with the development of technology of quantum memory, a local quantum network including a quantum memory unit will be available, as shown in Figure 1(b). The quantum memory unit involves some quantum systems other than optical systems, for example atomic [29][30][31] and solid state systems [32,33], so such a quantum network would be a hybrid quantum network consisting of different quantum systems. By connecting space separated local quantum networks together, we will have a global quantum Internet, as shown in Figure 1(c).…”

“…Quantum memory is an essential building block for quantum repeater and quantum network. Various mechanisms of quantum memory have been developed, such as electromagnetically induced transparency (EIT) [29,[112][113][114][115], atomic Raman memory [30,116,117], gradient echo memory (GEM) [31,118], and solid system [32,33,[119][120][121]. Different methods of quantum memory have their own advantages and they are rapidly developing in recent years.…”

“…Since the bandwidth of quantum memory with EIT is limited, broad bandwidth atomic Raman memory has been developed [30,116,117]. A memory efficiency of above 82% and an unconditional fidelity up to 98% were obtained for the atomic Raman memory [30].…”

Toward an ultrafast double-pulse stretcher–compressor

“…Quantum control has been utilized in many areas of science including quantum information [1,2], control of chemical reactions [3][4][5][6], and even high precision measurements [7][8][9]. Different schemes have been developed for the selective excitation of electronic, vibrational, and rotational states of atoms and molecules.…”

Raman quantum memory with built-in suppression of four-wave-mixing noise

“…This is a key element for future photonic quantum information protocols as a means to synchronise probabilistic processes via multiplexing, enabling secure long-distance communication through the distribution of entangled states [1]. Many impressive implementations of on-demand QM protocols have been demonstrated across various platforms including warm [2][3][4][5][6][7][8] and cold atomic vapours [9][10][11][12][13][14] and solidstate systems [15][16][17][18][19]. While considerable progress has been made to reach high efficiencies [11,13,16] and long storage times [9,17], designing a memory protocol that does not add noise to the recalled signal remains a significant challenge.…”