Experimental noiseless linear amplification using weak measurements

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Author(s)
Ho, Joseph
Boston, Allen
Palsson, Matthew
Pryde, Geoff
Year published
2016
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Show full item recordAbstract
The viability of quantum communication schemes rely on sending quantum states of light over long
distances. However, transmission loss can degrade the signal strength, adding noise. Heralded
noiseless amplification of a quantum signal can provide a solution by enabling longer direct
transmission distances and by enabling entanglement distillation. The central idea of heralded
noiseless amplification—a conditional modification of the probability distribution over photon
number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak
measurement, learning partial information about an observable ...
View more >The viability of quantum communication schemes rely on sending quantum states of light over long distances. However, transmission loss can degrade the signal strength, adding noise. Heralded noiseless amplification of a quantum signal can provide a solution by enabling longer direct transmission distances and by enabling entanglement distillation. The central idea of heralded noiseless amplification—a conditional modification of the probability distribution over photon number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak measurement, learning partial information about an observable leads to a conditional back-action of a commensurate size. Here we experimentally investigate the application of weak, or variable-strength, measurements to the task of heralded amplification, by using a quantum logic gate to weakly couple a small single-optical-mode quantum state (the signal) to an ancilla photon (the meter). The weak measurement is carried out by choosing the measurement basis of the meter photon and, by conditioning on the meter outcomes, the signal is amplified.Wecharacterise the gain of the amplifier as a function of the measurement strength, and use interferometric methods to show that the operation preserves the coherence of the signal.
View less >
View more >The viability of quantum communication schemes rely on sending quantum states of light over long distances. However, transmission loss can degrade the signal strength, adding noise. Heralded noiseless amplification of a quantum signal can provide a solution by enabling longer direct transmission distances and by enabling entanglement distillation. The central idea of heralded noiseless amplification—a conditional modification of the probability distribution over photon number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak measurement, learning partial information about an observable leads to a conditional back-action of a commensurate size. Here we experimentally investigate the application of weak, or variable-strength, measurements to the task of heralded amplification, by using a quantum logic gate to weakly couple a small single-optical-mode quantum state (the signal) to an ancilla photon (the meter). The weak measurement is carried out by choosing the measurement basis of the meter photon and, by conditioning on the meter outcomes, the signal is amplified.Wecharacterise the gain of the amplifier as a function of the measurement strength, and use interferometric methods to show that the operation preserves the coherence of the signal.
View less >
Journal Title
New Journal of Physics
Volume
18
Copyright Statement
©2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is an Open Access article distributed under the terms of the Creative Commons Attribution 3.0 Unported (CC BY 3.0) License (https://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Subject
Physical Sciences not elsewhere classified
Physical Sciences