Abstract
We present an experimental demonstration of a practical nondeterministic quantum optical amplification scheme that employs two mature technologies, state comparison and photon subtraction, to achieve amplification of known sets of coherent states with high fidelity. The amplifier uses coherent states as a resource rather than single photons, which allows for a relatively simple light source, such as a diode laser, providing an increased rate of amplification. The amplifier is not restricted to low amplitude states. With respect to the two key parameters, fidelity and the amplified state production rate, we demonstrate significant improvements over previous experimental implementations, without the requirement of complex photonic components. Such a system may form the basis of trusted quantum repeaters in nonentanglement-based quantum communications systems with known phase alphabets, such as quantum key distribution or quantum digital signatures.
Highlights
Classical electromagnetic signals can, in principle, be amplified by any gain factor without being compromised by noise, allowing transmission losses to be overcome and signals to be transmitted further
We present an experimental demonstration of a practical nondeterministic quantum optical amplification scheme that employs two mature technologies, state comparison and photon subtraction, to achieve amplification of known sets of coherent states with high fidelity
Such a system may form the basis of trusted quantum repeaters in nonentanglement-based quantum communications systems with known phase alphabets, such as quantum key distribution or quantum digital signatures
Summary
In principle, be amplified by any gain factor without being compromised by noise, allowing transmission losses to be overcome and signals to be transmitted further. The noise-addition scheme removes the requirement for single photons and works well as a phase concentrator, but the fidelity of the output state compared to a perfectly amplified version of the input state is typically low [10,12,16].
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