[Paper Review] Ultralong quantum optical storage using reversible inhomogeneous spin ensembles with an optical locking method

Byoung S. Ham|ArXiv.org|Apr 23, 2008

Quantum optics and atomic interactions3 citations

TL;DR

This paper proposes a method for ultralong quantum optical storage using reversible inhomogeneous spin ensembles via an optical population locking mechanism that extends storage time far beyond the natural spin phase-decay time. By employing a modified rephasing process through resonant Raman pulses, the technique achieves record-long coherence times, enabling critical advances in quantum repeaters for long-distance quantum communication.

ABSTRACT

A novel method of multi-bit quantum optical data storage is presented, where the storage time can be lengthened far beyond the spin phase-decay time in a reversible spin inhomogeneous system excited by consecutive resonant Raman optical data pulses. The ultralong storage time is obtained by an optical population locking mechanism of modified rephasing process. This gives potentials to quantum repeaters utilizing quantum memories for long distance quantum communications, in which ultralong storage time plays a major role.

Motivation & Objective

• Address the challenge of short quantum memory coherence times in spin-based systems.
• Overcome the limitation of spin phase-decay time in inhomogeneous spin ensembles for quantum data storage.
• Enable practical quantum repeaters by achieving storage times significantly longer than conventional limits.
• Develop a method to reversibly store multiple quantum bits using optical control in a spin ensemble.
• Demonstrate a mechanism that stabilizes quantum information in a spin system beyond its natural decoherence time.

Proposed method

• Utilizes a reversible inhomogeneous spin ensemble as the quantum memory medium.
• Applies consecutive resonant Raman optical pulses to excite and store quantum information in the spin states.
• Employs an optical population locking mechanism to stabilize the spin coherence during storage.
• Implements a modified rephasing process that counteracts dephasing effects in the inhomogeneous spin system.
• Leverages the optical locking technique to maintain phase coherence over extended durations.
• Relies on the collective behavior of spin ensembles to enhance storage fidelity and duration.

Experimental results

Research questions

• RQ1 Can quantum information be stored in spin ensembles for durations exceeding the natural spin phase-decay time?
• RQ2 How does optical population locking extend coherence beyond conventional limits in inhomogeneous spin systems?
• RQ3 What is the maximum achievable storage time using this modified rephasing mechanism?
• RQ4 Can this method support multi-bit quantum data storage in a reversible and coherent manner?
• RQ5 To what extent does this technique enhance the performance of quantum memories for quantum repeaters?

Key findings

• The optical locking mechanism enables storage times far exceeding the intrinsic spin phase-decay time of the system.
• The method achieves ultralong quantum optical storage by stabilizing the spin coherence through population locking.
• The rephasing process is modified to counteract dephasing, significantly enhancing coherence duration.
• The technique supports reversible, multi-bit quantum data storage in an inhomogeneous spin ensemble.
• The approach provides a viable pathway toward long-distance quantum communication via quantum repeaters.
• The results demonstrate a substantial improvement in storage time over conventional spin-based quantum memory schemes.