Coherent optical memory with GHz bandwidth

Klaus F. Reim, Joshua Nunn, Virginia O. Lorenz +5 more

We demonstrate the coherent storage and retrieval of sub-nanosecond low-intensity light pulses with spectral bandwidths exceeding 1 GHz in cesium vapor, using the novel, far off-resonant two-photon Raman memory protocol.

James Vinton Burt

Kai Shinbrough, B. D. Hunt, Sehyun Park +4 more

We demonstrate quantum memory of single-photon-level coherent pulses of 880 GHz bandwidth with 95.6(3)% storage efficiency in collisionally broadened barium vapor. We measure 26(1)% total efficiency, limited by control field power; 0.49(1) ns memory lifetime, limited by motional dephasing; and a signal-to-noise ratio of ${O}(10^{3})$, limited by two-photon control field scattering. To the best of the authors’ knowledge, this represents the best efficiency, lifetime, and noise performance of atomic quantum memories in the ultrabroadband regime $(\gt100$ GHz bandwidth) to date.

Rachel Pei Chin Won

Filip Sośnicki, Michał Karpiński

A promising approach towards implementation of large-scale quantum information and communication protocols is a multifunctional photonic quantum information processing system, where a variety of distributed components, such as quantum memories, trapped ions, or photonic quantum gates are coherently interconnected via photonic links. These components may exhibit a vast range of spectro-temporal properties. A key incompatibility is spectral bandwidth mismatch. For example the characteristic bandwidths of photonic communication channels and nonlinear-optical single-photon sources are in the 100 GHz range, whereas typical bandwidths associated with trapped ions or media exhibiting strong single photon nonlinearity, such as Rydberg atoms, are in the sub-GHz regime, reaching single MHz values. Single-photon-level bandwidth conversion has been experimentally demonstrated by techniques based on the temporal lensing principle, but only between multi-GHz bandwidth optical pulses [1, 2]. Here we present a numerical study of an electro-optic time-lens-based technique enabling bandwidth conversion from the 100 GHz bandwidth region towards single MHz bandwidths. We discuss progress towards experimental implementation and possible realizations using alternative temporal lensing platforms, such as three and four wave mixing.

Alexander I. Lvovsky, Barry C. Sanders, Wolfgang Tittel