Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
  • Letter

Optimizing the efficiency of a quantum memory based on rephased amplified spontaneous emission

Charlotte K. Duda, Kate R. Ferguson, Rose L. Ahlefeldt, Morgan P. Hedges, and Matthew J. Sellars
Phys. Rev. A 107, L030602 – Published 7 March 2023
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • EXPERIMENTAL SETUP
  • OPTICAL DEPTH MEASUREMENTS
  • REPHASING EFFICIENCY MEASUREMENTS
  • INSEPARABILITY MEASUREMENT
  • CONCLUSION
  • ACKNOWLEDGMENTS
    • References

    Abstract

    We studied the recall efficiency as a function of optical depth of rephased amplified spontaneous emission (RASE), a protocol for generating entangled light. The experiments were performed on the H43→D21 transition in the rare-earth doped crystal Pr3+:Y2SiO5, using a four-level echo sequence between four hyperfine levels to rephase the emission. The efficiency of RASE was observed to increase from 3% to 14% as the optical depth was reduced from 2.0 to 0.8. This is a significant improvement over the previously reported nonclassical result but is well short of the predicted efficiency. We discuss the possible mechanisms limiting the protocol's performance, and suggest ways to overcome these limits.

    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Received 7 July 2022
    • Revised 17 January 2023
    • Accepted 21 February 2023

    DOI:https://doi.org/10.1103/PhysRevA.107.L030602

    ©2023 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Entanglement productionQuantum communicationQuantum information with solid state qubitsQuantum memories
    1. Physical Systems
    Rare-earth doped crystals
    Quantum Information, Science & Technology

    Authors & Affiliations

    Charlotte K. Duda, Kate R. Ferguson, Rose L. Ahlefeldt, Morgan P. Hedges, and Matthew J. Sellars

    • Centre for Quantum Computation and Communication Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia

    Article Text (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 107, Iss. 3 — March 2023

    Reuse & Permissions
    Access Options
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      (a) Experimental setup showing the control and local oscillator (LO) arms of the optical setup. HWP and QWP are half and quarter wave plates, respectively, and BS is the beam splitter. (b) Hyperfine structure of the optical ground and excited states of Pr3+:Y2SiO5 in zero field with transitions used for the RASE and inverted four-level echo (I4LE) indicated. The transitions have relative oscillator strengths of 0.05 for |g1〉↔|e1〉, 0.40 for |g2〉↔|e1〉, 0.55 for |g3〉↔|e1〉, 0.60 for |g2〉↔|e2〉, and 0.38 for |g3〉↔|e2〉 [17]. (c) The pulse sequence used for RASE and I4LE. The 10-µs windows used for calculating the ASE and RASE quadrature values are shown. The rephasing pulses (π1 and π2) were 1.7 and 2.5µs long, respectively.

      Reuse & Permissions
    • Figure 2
      Figure 2

      Spectrum of the amplified (pink) and rephased (blue) signals are shown with the respective background levels (dashed) at an optical depth of 1.4. (a) The RASE experiment, where the prepared feature amplifies the vacuum state. (b) The I4LE experiment, where the spectrum has been normalized to the input pulse.

      Reuse & Permissions
    • Figure 3
      Figure 3

      Optical depth measured after the inversion pulse via two measures: The optical depth seen by a probe pulse compared to the average variance of the ASE signal. 1σ error in x is shown (the y error is negligible). The model was constructed using Eq. (1).

      Reuse & Permissions
    • Figure 4
      Figure 4

      Efficiency of RASE and inverted four-level echo (I4LE) with optical depth. The I4LE result was calculated using the emission spectrum while RASE result was calculated using the photon count. 1σ error in y is shown (the x error is negligible). The model was constructed using Eq. (2). Both the I4LE result and model are scaled to the optical delay time used in the RASE experiment using the measured optical decay constant.

      Reuse & Permissions
    • Figure 5
      Figure 5

      The inseparability criterion [see Eq. (5)] as a function of weighting parameter [see Eq. (3)] for different optical depths αL. Solid lines show the experimental result and 1σ error averaging over 9000 measurements using τs=5µs, and dashed lines show the model. Further detail on the calculation method can be found in Refs. [9, 11].

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review A

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×