Cascading quantum light-matter interfaces with minimal interconnection losses

Mehdi Namazi, Thomas Mittiga, Connor Kupchak, and Eden Figueroa

Phys. Rev. A 92, 033846 – Published 24 September 2015

Abstract

The ability to interface multiple optical quantum devices is a key milestone towards the development of future quantum information processors and networks. One of the requirements for any of their constituent elements will be cascadability, i.e., the ability to drive the input of a device using the output of another one. Here, we report the cascading of quantum light-matter interfaces by storing few-photon level pulses of light in warm vapor followed by the subsequent storage of the retrieved field onto a second ensemble. We demonstrate that by using built-in purification mechanisms in the sequential storage, the final signal-to-background ratio can remain greater than one for weak pulses containing eight input photons on average.

Received 10 March 2015
Revised 19 June 2015

DOI:https://doi.org/10.1103/PhysRevA.92.033846

Authors & Affiliations

Mehdi Namazi, Thomas Mittiga, Connor Kupchak, and Eden Figueroa

Department of Physics and Astronomy, Stony Brook University, New York, 11794-3800, USA

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Issue

Vol. 92, Iss. 3 — September 2015

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Images

Figure 1
(a) Concept of the cascaded storage with two light-matter interfaces. (b) First storage: Input pulse (dashed line [blue online]), control field 1 time sequence (dot-dashed line [black online]), and retrieved light signal (solid line [green online]) as obtained by simulation. (c) Second storage: control field 2 time sequence (dot-dashed line [black online], notice the time delay with respect to control field 1) and cascaded retrieved signal (solid line [red online]).
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Figure 2
(a) Atomic level scheme and EIT configuration used in both memories. (b) Experimental setup for successive storage of pulses at the few-photon level, including the stages of control filtering. AOM, acousto-optical modulator; BD, beam displacer; GLP, Glan laser polarizer; FR, Faraday rotator; SPCM, single-photon-counting module; L, lens; M, mirror; NPBS, nonpolarizing beam splitter. Probe, gray beam paths [red online]; control, light gray beam paths [yellow online]. The NPBS transmits 10% of the first stored pulse through the filtering system to be characterized and sends 90% back to the second rail for a successive storage.
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Figure 3
Successive storage of classical pulses. Thin gray line [blue online]: input pulse; gray line [green online]: rail 1 single storage signal; thick gray line [red online]: rail 2 cascaded storage signal. The gray line [green online] is scaled by a factor 0.26 to account for different propagation losses after the first and second rails. Inset: dependency of storage efficiencies on the full-with half maximum of the Gaussian shaped retrieved field for the first storage. Squares [blue online]: efficiency of the first storage $η_{1}$ ; circles [red online]: efficiency of the second storage $η_{2}$ ; and triangles [purple online]: overall efficiency of cascaded storage procedures $η_{T}$ .
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Figure 4
Cascaded optical storage for input pulses containing eight photons per pulse on average. Dashed line [green online]: input pulse (measured in SPCM 2); light gray line [purple online]: absorbed pulse (measured in SPCM 2); white bars histogram: retrieved pulse after first storage (measured in SPCM 1 scaled by a factor 0.26); gray bars histogram [blue online]: retrieved signal after cascaded storage procedure (with background, measured in SPCM 2); light gray bars histogram [blue online]: background-only measurement. Inset: The effect of reshaping the control field for the optical retrieval in the first rail. Storage using on-off modulation of control field 1 (grey bars histogram [blue online]) and storage counts obtained with a temporally modulated control field 1 (white bars histogram). The temporal shape of the control field 1 is indicated by the dotted black line.
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Figure 5
Total cascaded storage efficiency $η_{T}$ (gray line [blue online]) and cascaded SBR (dashed gray line [red online]) vs optical power for first retrieval. Inset: SBR of first storage event vs optical power for first retrieval (purple online).
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Physical Review A

covering atomic, molecular, and optical physics and quantum information