Observation of the dynamical Casimir effect in a superconducting circuit

By C. Wilson, G. Johansson, A. Pourkabirian, M. Simoen, J. Johansson, T. Duty, Franco Nori, Per Delsing. Nature, 2011

863 citations recorded by the source corpus.

One of the most surprising predictions of modern quantum theory is that the vacuum of space is not empty. In fact, quantum theory predicts that it teems with virtual particles flitting in and out of existence. Although initially a curiosity, it was quickly realized that these vacuum fluctuations had measurable consequences—for instance, producing the Lamb shift of atomic spectra and modifying the magnetic moment of the electron. This type of renormalization due to vacuum fluctuations is now central to our understanding of nature. However, these effects provide indirect evidence for the existence of vacuum fluctuations. From early on, it was discussed whether it might be possible to more directly observe the virtual particles that compose the quantum vacuum. Forty years ago, it was suggested that a mirror undergoing relativistic motion could convert virtual photons into directly observable real photons. The phenomenon, later termed the dynamical Casimir effect, has not been demonstrated previously. Here we observe the dynamical Casimir effect in a superconducting circuit consisting of a coplanar transmission line with a tunable electrical length. The rate of change of the electrical length can be made very fast (a substantial fraction of the speed of light) by modulating the inductance of a superconducting quantum interference device at high frequencies (>10 gigahertz). In addition to observing the creation of real photons, we detect two-mode squeezing in the emitted radiation, which is a signature of the quantum character of the generation process.

Subfields: Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/144e423e111963eed4a931e7797ecefed49b2ca5

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

Citations in the corpus

Quantum Simulation (2013, background): “such as the dynamical Casimir effect (Johansson et al., 2010; Lähteenmäki et al., 2013; Wilson et al., 2011).”
Nano Superconducting Quantum Interference device: a powerful tool for nanoscale investigations (2015, neutral): “roaches the quantum limit. The ultra high SQUID sensitivity has also allowed, in the last years, very interesting experiments like the detection of axion dark-matter [5], the dynamical Casimir effect [6], the Majorana fermions [7] investigations, the Josephson heat interferometer [8], the Sunyaev Ze”
Subradiant states of quantum bits coupled to a one-dimensional waveguide (2018, background): “Such systems enable a number of exotic phenomena that are difficult to observe or have no obvious analogue in other settings, such as near-perfect reflection of light from a single resonant qubit [1, 2, 4, 12–14], or the dynamical Casimir effect [15], and allow for the measurement of quantum vacuum ”
Dynamical Casimir effect in a Josephson metamaterial (2011, background): “The cavity (with parameters such as resonant frequency and external/internal decay rates that can be extracted from separate reflection measurements) produces a resonant enhancement of the DCE effect; thus, our system offers a significant amendment over the alternative realizations of DCE based on c”
Microwave photonics with superconducting quantum circuits (2017, methodology): “After a theoretical study showed that SQUID amplifiers can display directionality [237], directional amplification has been realized with two Josephson parametric converters (JPCs, four resonators coupled via a ring interrupted by four Josephson junctions) pumped with two microwave tones [238, 239];”
Quantum coherence and geometric quantum discord (2017, methodology): “The modulation of boundary condition, theoretically created by a mirror at relativistic speeds, was achieved by high-frequency modulation of the external magnetic flux threading a superconducting quantum interferometric device (Wilson et al., 2011).”
The Quantum Vacuum (2014, methodology): “It is the variation of geometry, either as a change in boundary conditions (Wilson et al., 2011) or as a change in the speed of light (and therefore the metric) (Lähteenmäki et al.”