24 research outputs found
Microscopy with undetected photons in the mid-infrared
Owing to its capacity for unique (bio)-chemical specificity, microscopy
withmid-IR illumination holds tremendous promise for a wide range of biomedical
and industrial applications. The primary limitation, however, remains
detection; with current mid-IR detection technology often marrying inferior
technical capabilities with prohibitive costs. This has lead to approaches that
shift detection towavelengths into the visible regime, where vastly superior
silicon-based cameratechnology is available. Here, we experimentally show how
nonlinear interferometry with entangled light can provide a powerful tool for
mid-IR microscopy, while only requiring near-infrared detection with a standard
CMOS camera. In this proof-of-principle implementation, we demonstrate
intensity imaging overa broad wavelength range covering 3.4-4.3um and
demonstrate a spatial resolution of 35um for images containing 650 resolved
elements. Moreover, we demonstrate our technique is fit for purpose, acquiring
microscopic images of biological tissue samples in the mid-IR. These results
open a new perspective for potential relevance of quantum imaging techniques in
the life sciences.Comment: back-to-back submission with arXiv:2002.05956, Anna V. Paterova,
Sivakumar M. Maniam, Hongzhi Yang, Gianluca Grenci, and Leonid A. Krivitsky,
"Hyperspectral Infrared Microscopy With Visible Light
Gaussian Optical Ising Machines
It has recently been shown that optical parametric oscillator (OPO) Ising
machines, consisting of coupled optical pulses circulating in a cavity with
parametric gain, can be used to probabilistically find low-energy states of
Ising spin systems. In this work, we study optical Ising machines that operate
under simplified Gaussian dynamics. We show that these dynamics are sufficient
for reaching probabilities of success comparable to previous work. Based on
this result, we propose modified optical Ising machines with simpler designs
that do not use parametric gain yet achieve similar performance, thus
suggesting a route to building much larger systems.Comment: 6 page
Low-noise quantum frequency conversion in a monolithic bulk ppKTP cavity
Interfacing the different building blocks of a future large scale quantum
network will demand efficient and noiseless frequency conversion of quantum
light. Nitrogen-vacancy (NV) centers in diamond are a leading candidate to form
the nodes of such a network. However, the performance of a suitable converter
remains a bottleneck, with existing demonstrations severely limited by
parasitic noise arising at the target telecom wavelength. Here, we demonstrate
a new platform for efficient low-noise quantum frequency conversion based on a
monolithic bulk ppKTP cavity and show its suitability for the conversion of 637
nm single photons from NV centers in diamond to telecommunication wavelengths.
By resonantly enhancing the power of an off-the-shelf pump laser, we achieve an
internal conversion efficiency of while generating only
(110\pm 4) \mbox{ kHz/nm} noise at the target wavelength without the need for
any active stabilization. This constitutes a 5-fold improvement in noise over
existing state-of-the-art single-step converters at this wavelengths. We verify
the almost ideal preservation of non-classical correlations by converting
photons from a spontaneous parametric down-conversion source and moreover show
the preservation of time-energy entanglement via Franson interferometry.Comment: 7 pages, 6 figures, 2 table
Measurement-Based Noiseless Linear Amplification for Quantum Communication
Entanglement distillation is an indispensable ingredient in extended quantum
communication networks. Distillation protocols are necessarily
non-deterministic and require advanced experimental techniques such as
noiseless amplification. Recently it was shown that the benefits of noiseless
amplification could be extracted by performing a post-selective filtering of
the measurement record to improve the performance of quantum key distribution.
We apply this protocol to entanglement degraded by transmission loss of up to
the equivalent of 100km of optical fibre. We measure an effective entangled
resource stronger than that achievable by even a maximally entangled resource
passively transmitted through the same channel. We also provide a
proof-of-principle demonstration of secret key extraction from an otherwise
insecure regime. The measurement-based noiseless linear amplifier offers two
advantages over its physical counterpart: ease of implementation and near
optimal probability of success. It should provide an effective and versatile
tool for a broad class of entanglement-based quantum communication protocols.Comment: 7+3 pages, 5+1 figures, close to published versio
Heralded quantum steering over a high-loss channel
Entanglement is the key resource for many long-range quantum information
tasks, including secure communication and fundamental tests of quantum physics.
These tasks require robust verification of shared entanglement, but performing
it over long distances is presently technologically intractable because the
loss through an optical fiber or free-space channel opens up a detection
loophole. We design and experimentally demonstrate a scheme that verifies
entanglement in the presence of at least dB of added loss,
equivalent to approximately km of telecommunication fiber. Our protocol
relies on entanglement swapping to herald the presence of a photon after the
lossy channel, enabling event-ready implementation of quantum steering. This
result overcomes the key barrier in device-independent communication under
realistic high-loss scenarios and in the realization of a quantum repeater.Comment: 8 pages, 5 figure