25 research outputs found
Variance-Based Sensitivity Analysis of -type Quantum Memory
The storage and retrieval of photonic quantum states, quantum memory, is a
key resource for a wide range of quantum applications. Here we investigate the
sensitivity of -type quantum memory to experimental fluctuations and
drift. We use a variance-based approach, focusing on the effects of
fluctuations and drift on memory efficiency. We consider shot-to-shot
fluctuations of the memory parameters, and separately we consider longer
timescale drift of the control field parameters. We find the parameters that a
quantum memory is most sensitive to depend on the quantum memory protocol being
employed, where the observed sensitivity agrees with physical interpretation of
the protocols. We also present a general framework that is applicable to other
figures of merit beyond memory efficiency. These results have practical
ramifications for quantum memory experiments.Comment: 8 pages, 6 figures, submitted to PR
Astronomical interferometry using continuous variable quantum teleportation
We propose a method to build an astronomical interferometer using continuous
variable quantum teleportation to overcome the transmission loss between
distant telescopes. The scheme relies on two-mode squeezed states shared by
distant telescopes as entanglement resources, which are distributed using
continuous variable quantum repeaters. We find the optimal measurement on the
teleported states, which uses beam-splitters and photon-number-resolved
detection. Compared to prior proposals relying on discrete states, our scheme
has the advantages of using linear optics to implement the scheme without
wasting stellar photons and making use of multiphoton events, which are
regarded as noise in previous discrete schemes.Comment: 15 pages, 7 figure
Broadband Quantum Memory in Atomic Ensembles
Broadband quantum memory is critical to enabling the operation of emerging
photonic quantum technology at high speeds. Here we review a central challenge
to achieving broadband quantum memory in atomic ensembles -- what we call the
'linewidth-bandwidth mismatch' problem -- and the relative merits of various
memory protocols and hardware used for accomplishing this task. We also review
the theory underlying atomic ensemble quantum memory and its extensions to
optimizing memory efficiency and characterizing memory sensitivity. Finally, we
examine the state-of-the-art performance of broadband atomic ensemble quantum
memories with respect to three key metrics: efficiency, memory lifetime, and
noise.Comment: 40 pages, 11 figures, submitted to Advances in AMO Physic
High-efficiency, high-speed, and low-noise photonic quantum memory
We present a demonstration of simultaneous high-efficiency, high-speed, and
low-noise operation of a photonic quantum memory. By leveraging controllable
collisional dephasing in a neutral barium atomic vapor, we demonstrate a
significant improvement in memory efficiency and bandwidth over existing
techniques. We achieve greater than 95% storage efficiency and 26% total
efficiency of 880 GHz bandwidth photons, with noise
photons per retrieved pulse. These ultrabroad bandwidths enable rapid quantum
information processing and contribute to the development of practical quantum
memories with potential applications in quantum communication, computation, and
networking
Fiber-based photon pair generation: a tutorial
The purpose of this tutorial paper is to present a broad overview of
photon-pair generation through the spontaneous four wave mixing (SFWM) process
in optical fibers. Progress in optical fiber technology means that today we
have at our disposal a wide variety of types of fiber, which together with the
fact that SFWM uses two pump fields, implies a truly remarkable versatility in
the resulting possible photon-pair properties. We discuss how the interplay of
the frequency, transverse mode, and polarization degrees of freedom, the first
linked to the latter two through fiber dispersion, leads to interesting
entanglement properties both in individual degrees of freedom and also
permitting hybrid and hyper entanglement in combinations of degrees of freedom.
This tutorial covers methods for photon pair factorability, frequency
tunability, and SFWM bandwidth control, the effect of frequency non-degenerate
and counter-propagating pumps, as well methods for characterizing photon pairs
generated in optical fibers.Comment: 21 pages, 9 figure