quantum memory

Reducing noise in a Raman quantum memory

Reducing noise in a Raman quantum memory

By Paul

New paper in Optics Letters:

Reducing noise in a Raman quantum memory

Philip J. Bustard, Duncan G. England, Khabat Heshami, Connor Kupchak, and Benjamin J. Sussman

Optics Letters Vol. 41, Issue 21, pp. 5055-5058 (2016)

https://doi.org/10.1364/OL.41.005055

Optical quantum memories are an important component of future optical and hybrid quantum technologies. Raman schemes are strong candidates for use with ultrashort optical pulses due to their broad bandwidth; however, the elimination of deleterious four-wave mixing noise from Raman memories is critical for practical applications. Here, we demonstrate a quantum memory using the rotational states of hydrogen molecules at room temperature. Polarization selection rules prohibit four-wave mixing, allowing the storage and retrieval of attenuated coherent states with a mean photon number 0.9 and a pulse duration 175 fs. The 1/𝑒 memory lifetime is 85.5 ps, demonstrating a time-bandwidth product of ≈480 in a memory that is well suited for use with broadband heralded down-conversion and fiber-based photon sources.

Phonon-Mediated Nonclassical Interference in Diamond

Phonon-Mediated Nonclassical Interference in Diamond

By Paul

New paper in PRL:

Phonon-Mediated Nonclassical Interference in Diamond

Duncan G. England, Kent A. G. Fisher, Jean-Philippe W. MacLean, Philip J. Bustard, Khabat Heshami, Kevin J. Resch, and Benjamin J. Sussman
Phys. Rev. Lett. 117, 073603 – Published 11 August 2016

 

Quantum interference of single photons is a fundamental aspect of many photonic quantum processing and communication protocols. Interference requires that the multiple pathways through an interferometer be temporally indistinguishable to within the coherence time of the photon. In this Letter, we use a diamond quantum memory to demonstrate interference between quantum pathways, initially temporally separated by many multiples of the optical coherence time. The quantum memory can be viewed as a light-matter beam splitter, mapping a THz-bandwidth single photon to a variable superposition of the output optical mode and stored phononic mode. Because the memory acts both as a beam splitter and as a buffer, the relevant coherence time for interference is not that of the photon, but rather that of the memory. We use this mechanism to demonstrate nonclassical single-photon and two-photon interference between quantum pathways initially separated by several picoseconds, even though the duration of the photons themselves is just ∼250  fs.

Quantum memories: emerging applications and recent advances

Quantum memories: emerging applications and recent advances

By Paul

New article in the Journal of Modern Optics

Pages 2005-2028 | Received 06 Nov 2015, Accepted 27 Dec 2015, Published online: 16 Mar 2016
DOI: 10.1080/09500340.2016.1148212

 

Quantum light–matter interfaces are at the heart of photonic quantum technologies. Quantum memories for photons, where non-classical states of photons are mapped onto stationary matter states and preserved for subsequent retrieval, are technical realizations enabled by exquisite control over interactions between light and matter. The ability of quantum memories to synchronize probabilistic events makes them a key component in quantum repeaters and quantum computation based on linear optics. This critical feature has motivated many groups to dedicate theoretical and experimental research to develop quantum memory devices. In recent years, exciting new applications, and more advanced developments of quantum memories, have proliferated. In this review, we outline some of the emerging applications of quantum memories in optical signal processing, quantum computation and non-linear optics. We review recent experimental and theoretical developments, and their impacts on more advanced photonic quantum technologies based on quantum memories.

 
 

DOI: 10.1080/09500340.2016.1148212
Also available via the arXiv, 1511.04018 (2015).
Light, meet matter @phys.org

Light, meet matter @phys.org

By Paul

Our recent quantum memory in diamond (PRL 2015) is picking up a bit of press, and has just been featured on phys.org:

“A quantum memory is a conversion between quantum states of light and matter,” Sussman tells Phys.org. “However, decoherence is constantly destroying the crucial quantum nature of the matter system, and thus the advantages of quantum technologies….”

Read the full article at phys.org