Colloquium: Stimulating uncertainty: Amplifying the quantum vacuum with superconducting circuits

Abstract

The ability to generate particles from the quantum vacuum is one of the most profound consequences of Heisenberg's uncertainty principle. Although the significance of vacuum fluctuations can be seen throughout physics, the experimental realization of vacuum amplification effects has until now been limited to a few cases. Superconducting circuit devices, driven by the goal to achieve a viable quantum computer, have been used in the experimental demonstration of the dynamical Casimir effect, and may soon be able to realize the elusive verification of analogue Hawking radiation. This article describes several mechanisms for generating photons from the quantum vacuum and emphasizes their connection to the well-known parametric amplifier from quantum optics. Discussed in detail is the possible realization of each mechanism, or its analogue, in superconducting circuit systems. The ability to selectively engineer these circuit devices highlights the relationship between the various amplification mechanisms.

A Gravitational Aharonov-Bohm Effect, and Its Connection to Parametric Oscillators and Gravitational Radiation

“…It should be stressed that the leftmost cavity, that is, the "single" Fabry-Perot resonator of Figure 4, is initially devoid of any radiation (i.e., it is initially an empty cavity), so that the emission of a macroscopic amount of signal microwaves through the left hole from the left side of the apparatus, would be a dramatic manifestation of the dynamical Casimir effect, in which the observed signal output must have built up exponentially starting solely from vacuum fluctuations inside this initially empty resonator. Since the dynamical Casimir effect is closely related to Hawking radiation according to [32], an observation of parametric oscillation resulting from the moving SC membrane in Figure 4 would be a very interesting result from the point of view of quantum field theory.…”

Effect of Higher-Order Nonlinearities on Amplification and Squeezing in Josephson Parametric Amplifiers

“…This modulates the effective length of the cavity and, as a consequence, its frequency. This modulation acts as an external source of energy leading to parametric amplification [40,41].…”

Phase sticking in one-dimensional Josephson junction chains

“…These properties are utilized for various applications such as the development of the Fluxonion for quantum information precessing 5 , development of voltage standards in metrology 6 and for widely tunable parametric amplifiers 7 . Furthermore it is suggested that very long one-dimensional Josephson junction chains formed in a transmission line geometry can be employed for creating an analog of the event horizon and Hawking radiation 8,9 .…”