Quantum Amplifiers and Generators

Dmitri A. Kouznetsov, Roberto Ortega-Martı́nez, Daniel Rohrlich

Any quantum device that amplifies coherent states of a field while preserving their phase generates noise. A nonlinear, phase-invariant amplifier may generate less noise, over a range of input field strengths, than any linear amplifier with the same amplification. We present explicit examples of such nonlinear amplifiers and derive lower bounds on the noise generated by a nonlinear, phase-invariant quantum amplifier.

Anders Karlsson, L. Gillner, E. Goobar +1 more

Nicolai G. Basov

Y P Chechenina, I R Katseva

Abstract : The authors calculate the emission produced by a generator-amplifier system with allowance for their mutual influence (i.e., the feedback between the generator and the amplifier), for different parameters of the active medium and of the resonator. The properties of such a system are compared with those of a system in which the quantum generator and the quantum amplifier are considered separately, so as to determine the region of parameters in which the feedback must be taken into account. The calculation is based on energy relations with allowance for the dependence of the gain of the active medium on the radiation density. The investigation shows that the mutual influence of the generator and the amplifier in such a compound system must be taken into account if the amplifier length is shorter than or equal to the length of the driver generator, or when the amplifying section is long but the reflection coefficients are close to the threshold values.

Anonymous

Raphael C. Pooser

A quantum random number generator (QRNG) and a photon generator for a QRNG are provided. The photon generator may be operated in a spontaneous mode below a lasing threshold to emit photons. Photons emitted from the photon generator may have at least one random characteristic, which may be monitored by the QRNG to generate a random number. In one embodiment, the photon generator may include a photon emitter and an amplifier coupled to the photon emitter. The amplifier may enable the photon generator to be used in the QRNG without introducing significant bias in the random number and may enable multiplexing of multiple random numbers. The amplifier may also desensitize the photon generator to fluctuations in power supplied thereto while operating in the spontaneous mode. In one embodiment, the photon emitter and amplifier may be a tapered diode amplifier.