gradient-echo-quantum-memory-in-warm-atomic-vapor

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

The Australian National University

Interferometric gravitational wave detectors are expected to be limited by shot noise at some frequencies. We experimentally demonstrate that a power recycled Michelson with squeezed light injected into the dark port can overcome this limit. An improvement in the signal-to-noise ratio of 2.3 dB is measured and locked stably for long periods of time. The configuration, control, and signal readout of our experiment are compatible with current gravitational wave detector designs. We consider the application of our system to long baseline interferometer designs such as LIGO.

Experimental demonstration of a squeezing-enhanced power-recycled michelson interferometer for gravitational wave detection.

We demonstrate theoretically that the resonance frequencies of high-Q microcavities in two-dimensional photonic crystal membranes can be tuned over a wide range by introducing a subwavelength dielectric tip into the cavity mode. Three-dimensional finite-difference time-domain simulations show that by varying the lateral and vertical positions of the tip, it is possible to tune the resonator frequency without lowering the quality factor. Excellent agreement with a perturbative theory is obtained, showing that the tuning range is limited by the ratio of the cavity mode volume to the effective polarizability of the nanoperturber.

Controlling the resonance of a photonic crystal microcavity by a near-field probe.

The bandwidth and versatility of optical devices have revolutionized information technology systems and communication networks. Precise and arbitrary control of an optical field that preserves optical coherence is an important requisite for many proposed photonic technologies. For quantum information applications, a device that allows storage and on-demand retrieval of arbitrary quantum states of light would form an ideal quantum optical memory. Recently, significant progress has been made in implementing atomic quantum memories using electromagnetically induced transparency, photon echo spectroscopy, off-resonance Raman spectroscopy and other atom-light interaction processes. Single-photon and bright-optical-field storage with quantum states have both been successfully demonstrated. Here we present a coherent optical memory based on photon echoes induced through controlled reversible inhomogeneous broadening. Our scheme allows storage of multiple pulses of light within a chosen frequency bandwidth, and stored pulses can be recalled in arbitrary order with any chosen delay between each recalled pulse. Furthermore, pulses can be time-compressed, time-stretched or split into multiple smaller pulses and recalled in several pieces at chosen times. Although our experimental results are so far limited to classical light pulses, our technique should enable the construction of an optical random-access memory for time-bin quantum information, and have potential applications in quantum information processing.

Coherent optical pulse sequencer for quantum applications.

We report on the performance of a dual-wavelength resonant, traveling-wave optical parametric oscillator to generate squeezed light for application in advanced gravitational-wave interferometers. Shot noise suppression of 8.6±0.8 dB was measured across the detection band of interest to Advanced LIGO, and controlled squeezing measured over 5900 s. Our results also demonstrate that the traveling-wave design has excellent intracavity backscattered light suppression of 47 dB and incident backscattered light suppression of 41 dB, which is a crucial design issue for application in advanced interferometers.

Article	Year
Experimental demonstration of a squeezing-enhanced power-recycled michelson interferometer for gravitational wave detection. Physical review letters\| PubMed ID: 12059348	2002
Controlling the resonance of a photonic crystal microcavity by a near-field probe. Physical review letters\| PubMed ID: 16241728	2005
Coherent optical pulse sequencer for quantum applications. Nature\| PubMed ID: 19741705	2009
Backscatter tolerant squeezed light source for advanced gravitational-wave detectors. Optics letters\| PubMed ID: 22139282	2011

Ben C. Buchler

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