1,959 research outputs found
Proposal for Implementing Device-Independent Quantum Key Distribution based on a Heralded Qubit Amplification
In device-independent quantum key distribution (DIQKD), the violation of a
Bell inequality is exploited to establish a shared key that is secure
independently of the internal workings of the QKD devices. An experimental
implementation of DIQKD, however, is still awaited, since hitherto all optical
Bell tests are subject to the detection loophole, making the protocol
unsecured. In particular, photon losses in the quantum channel represent a
fundamental limitation for DIQKD. Here, we introduce a heralded qubit amplifier
based on single-photon sources and linear optics that provides a realistic
solution to overcome the problem of channel losses in Bell tests.Comment: 5 pages, 4 figures, 6 page appendi
Integrated Photonic Sensing
Loss is a critical roadblock to achieving photonic quantum-enhanced
technologies. We explore a modular platform for implementing integrated
photonics experiments and consider the effects of loss at different stages of
these experiments, including state preparation, manipulation and measurement.
We frame our discussion mainly in the context of quantum sensing and focus
particularly on the use of loss-tolerant Holland-Burnett states for optical
phase estimation. In particular, we discuss spontaneous four-wave mixing in
standard birefringent fibre as a source of pure, heralded single photons and
present methods of optimising such sources. We also outline a route to
programmable circuits which allow the control of photonic interactions even in
the presence of fabrication imperfections and describe a ratiometric
characterisation method for beam splitters which allows the characterisation of
complex circuits without the need for full process tomography. Finally, we
present a framework for performing state tomography on heralded states using
lossy measurement devices. This is motivated by a calculation of the effects of
fabrication imperfections on precision measurement using Holland-Burnett
states.Comment: 19 pages, 7 figure
Integrated frequency comb source of heralded single photons
We report an integrated photon pair source based on a CMOS-compatible microring resonator that generates multiple, simultaneous, and independent photon pairs at different wavelengths in a frequency comb compatible with fiber communication wavelength division multiplexing channels (200 GHz channel separation) and with a linewidth that is compatible with quantum memories (110 MHz). It operates in a self-locked pump configuration, avoiding the need for active stabilization, making it extremely robust even at very low power levels
Heralded photon amplification for quantum communication
Heralded noiseless amplification based on single-photon sources and linear
optics is ideally suited for long-distance quantum communication tasks based on
discrete variables. We experimentally demonstrate such an amplifier, operating
at telecommunication wavelengths. Coherent amplification is performed with a
gain of G=1.98+/-0.2, for a state with a maximum expected gain G=2. We also
demonstrate that there is no need for a stable phase reference between the
initial signal state and the local auxiliary photons used by the amplifier.
These results highlight the potential of heralded quantum amplifiers for
long-distance quantum communication, and bring device-independent quantum key
distribution one step closer.Comment: 5 pages, 4 figure
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