A simulated photon-number detector in quantum information processing

2002 ◽  
Vol 2 (Special) ◽  
pp. 556-559
Author(s):  
K. Nemoto ◽  
S. Braunstein
Keyword(s):  
Quantum Information ◽  
Communication Channel ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Photon Number ◽  
Homodyne Detection ◽  
Fundamental Limit ◽  
Infrared Wavelengths ◽  
Set Up ◽  
Alternative Set

A simulated photon-number detection via homodyne detectors is considered as a way to improve the efficiency near the single-photon level of communication. Current photon-number detectors at infrared wavelengths are typically characterized by their low detection efficiencies, which significantly reduce the mutual information of a bosonic communication channel. In order to avoid the inefficiency inherent in such direct photon-number detection, we evaluate an alternative set-up based on efficient dual homodyne detection. We show that replacing inefficient direct detectors with homodyne-based simulated direct detectors can yield significant improvements, even near the single-photon level of operation. However we argue that there is a fundamental limit on the ability of homodyne detection to simulate ideal photon number detection, considering the exponential gap between quantum and classical computers. This applies to arbitrarily complicated simulation strategies based on homodyne detection.

scholarly journals Procedure via cross-Kerr nonlinearities for encoding single logical qubit information onto four-photon decoherence-free states

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jino Heo ◽  
Seong-Gon Choi
Keyword(s):  
Quantum Information ◽  
Quantum Information Processing ◽  
Photon Number ◽  
Optical Devices ◽  
Quantum Bus ◽  
Reliable Procedure ◽  
Optical Gates ◽  
Photon Loss ◽  
Decoherence Effect ◽  
Logical Qubit

AbstractWe propose a photonic procedure using cross-Kerr nonlinearities (XKNLs) to encode single logical qubit information onto four-photon decoherence-free states. In quantum information processing, a decoherence-free subspace can secure quantum information against collective decoherence. Therefore, we design a procedure employing nonlinear optical gates, which are composed of XKNLs, quantum bus beams, and photon-number-resolving measurements with linear optical devices, to conserve quantum information by encoding quantum information onto four-photon decoherence-free states (single logical qubit information). Based on our analysis in quantifying the affection (photon loss and dephasing) of the decoherence effect, we demonstrate the experimental condition to acquire the reliable procedure of single logical qubit information having the robustness against the decoherence effect.

scholarly journals Optical Chirality and Single-Photon Isolation

2020 ◽  
Author(s):  
Lei Tang ◽  
Keyu Xia
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Kerr Nonlinearity ◽  
Single Photons ◽  
Optical Isolation ◽  
Optical Chirality ◽  
Magneto Optical Effect ◽  
Quantum Optical

Optical isolation is important for protecting a laser from damage due to the detrimental back reflection of light. It typically relies on breaking Lorentz reciprocity and normally is achieved via the Faraday magneto-optical effect, requiring a strong external magnetic field. Single-photon isolation, the quantum counterpart of optical isolation, is the key functional component in quantum information processing, but its realization is challenging. In this chapter, we present all-optical schemes for isolating the backscattering from single photons. In the first scheme, we show the single-photon isolation can be realized by using a chiral quantum optical system, in which a quantum emitter asymmetrically couples to nanowaveguide modes or whispering-gallery modes with high optical chirality. Secondly, we propose a chiral optical Kerr nonlinearity to bypass the so-called dynamical reciprocity in nonlinear optics and then achieve room-temperature photon isolation with low insertion loss. The concepts we present may pave the way for quantum information processing in an unconventional way.

scholarly journals Coupling single emitters to quantum plasmonic circuits

Nanophotonics ◽  
2016 ◽  
Vol 5 (3) ◽  
pp. 483-495 ◽  
Author(s):  
Alexander Huck ◽  
Ulrik L. Andersen
Keyword(s):  
Quantum Information ◽  
Recent Progress ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Strong Light ◽  
Fundamental Physics ◽  
Single Photon Emitters ◽  
Quantum Sensing ◽  
Matter Interaction ◽  
Light Matter Interaction

AbstractIn recent years, the controlled coupling of single-photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic nonlinearity on a nanoscaled platform. In this article, we will review the recent progress on coupling single emitters to nanowires towards the construction of a new platform for strong light-matter interaction. The control over such a platform might open new doors for quantum information processing and quantum sensing at the nanoscale and for the study of fundamental physics in the ultrastrong coupling regime.

scholarly journals Harnessing temporal modes for multi-photon quantum information processing based on integrated optics

2017 ◽  
Vol 375 (2099) ◽  
pp. 20160244 ◽  
Author(s):  
G. Harder ◽  
V. Ansari ◽  
T. J. Bartley ◽  
B. Brecht ◽  
C. Silberhorn
Keyword(s):  
Integrated Optics ◽  
Frequency Conversion ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Photon Number ◽  
Integrated Optics Devices ◽  
Sum Frequency ◽  
Temporal Modes ◽  
Quantum Technology ◽  
Photon States

In the last few decades, there has been much progress on low loss waveguides, very efficient photon-number detectors and nonlinear processes. Engineered sum-frequency conversion is now at a stage where it allows operation on arbitrary temporal broadband modes, thus making the spectral degree of freedom accessible for information coding. Hereby the information is often encoded into the temporal modes of a single photon. Here, we analyse the prospect of using multi-photon states or squeezed states in different temporal modes based on integrated optics devices. We describe an analogy between mode-selective sum-frequency conversion and a network of spatial beam splitters. Furthermore, we analyse the limits on the achievable squeezing in waveguides with current technology and the loss limits in the conversion process. This article is part of the themed issue ‘Quantum technology for the 21st century’.

scholarly journals DECOHERENCE-FREE QUANTUM MEMORY FOR PHOTONIC STATE USING ATOMIC ENSEMBLES

2009 ◽  
Vol 07 (04) ◽  
pp. 811-820 ◽  
Author(s):  
FENG MEI ◽  
YA-FEI YU ◽  
ZHI-MING ZHANG
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Large Scale ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Quantum Memory ◽  
Single Photon Detection ◽  
Atomic Ensembles ◽  
Optical Elements ◽  
Photonic State

Large scale quantum information processing requires stable and long-lived quantum memories. Here, using atom-photon entanglement, we propose an experimentally feasible scheme to realize decoherence-free quantum memory with atomic ensembles, and show one of its applications, remote transfer of unknown quantum state, based on laser manipulation of atomic ensembles, photonic state operation through optical elements, and single-photon detection with moderate efficiency. The scheme, with inherent fault-tolerance to the practical noise and imperfections, allows one to retrieve the information in the memory for further quantum information processing within the reach of current technology.

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