Cavity quantum electrodynamics (cavity QED) is the study of the interaction between light confined in a reflective
cavity
Cavity may refer to:
Biology and healthcare
*Body cavity, a fluid-filled space in many animals where organs typically develop
**Gastrovascular cavity, the primary organ of digestion and circulation in cnidarians and flatworms
*Dental cavity or too ...
and atoms or other particles, under conditions where the quantum nature of photons is significant. It could in principle be used to construct a
quantum computer
Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though ...
.
The case of a single 2-level atom in the cavity is mathematically described by the
Jaynes–Cummings model
The Jaynes–Cummings model (sometimes abbreviated JCM) is a theoretical model in quantum optics. It describes the system of a two-level atom interacting with a quantized mode of an optical cavity (or a bosonic field), with or without the prese ...
, and undergoes
vacuum Rabi oscillation
A vacuum Rabi oscillation is a damped oscillation of an initially excited atom coupled to an electromagnetic resonator or cavity in which the atom alternately emits photon(s) into a single-mode electromagnetic cavity and reabsorbs them. The atom ...
s
, that is between an excited atom and
photons, and a ground state atom and
photons.
If the cavity is in resonance with the atomic transition, a half-cycle of oscillation starting with no photons coherently swaps the atom qubit's state onto the cavity field's,
, and can be repeated to swap it back again; this could be used as a single photon source (starting with an excited atom), or as an interface between an atom or
trapped ion quantum computer
A trapped ion quantum computer is one proposed approach to a large-scale quantum computer. Ions, or charged atomic particles, can be confined and suspended in free space using electromagnetic fields. Qubits are stored in stable electronic state ...
and optical
quantum communication
Quantum information science is an interdisciplinary field that seeks to understand the analysis, processing, and transmission of information using quantum mechanics principles. It combines the study of Information science with quantum mechanics, qu ...
.
Other interaction durations create
entanglement between the atom and cavity field; for example, a quarter-cycle on resonance starting from
gives the
maximally entangled state
Quantum entanglement is the phenomenon that occurs when a group of particles are generated, interact, or share spatial proximity in a way such that the quantum state of each particle of the group cannot be described independently of the state of ...
(a
Bell state
The Bell states or EPR pairs are specific quantum states of two qubits that represent the simplest (and maximal) examples of quantum entanglement; conceptually, they fall under the study of quantum information science. The Bell states are a form o ...
)
. This can in principle be used as a
quantum computer
Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though ...
, mathematically equivalent to a
trapped ion quantum computer
A trapped ion quantum computer is one proposed approach to a large-scale quantum computer. Ions, or charged atomic particles, can be confined and suspended in free space using electromagnetic fields. Qubits are stored in stable electronic state ...
with cavity photons replacing phonons.
Nobel Prize in Physics
The
2012 Nobel Prize for Physics was awarded to
Serge Haroche
Serge Haroche (born 11 September 1944) is a French-Moroccan physicist who was awarded the 2012 Nobel Prize for Physics jointly with David J. Wineland for "ground-breaking experimental methods that enable measuring and manipulation of individual q ...
and
David Wineland
David Jeffrey Wineland (born February 24, 1944) is an American Nobel-laureate physicist at the National Institute of Standards and Technology (NIST) physics laboratory. His work has included advances in optics, specifically laser-cooling trap ...
for their work on controlling quantum systems.
Haroche was born 1944 in Casablanca, Morocco, and in 1971 gained a PhD from Université Pierre et Marie Curie in Paris. He shares half of the prize for developing a new field called cavity quantum electrodynamics (CQED) – whereby the properties of an atom are controlled by placing it in an optical or microwave cavity. Haroche focused on microwave experiments and turned the technique on its head – using CQED to control the properties of individual photons.
In a series of ground-breaking experiments, Haroche used CQED to realize Schrödinger's famous cat experiment in which a system is in a superposition of two very different quantum states until a measurement is made on the system. Such states are extremely fragile, and the techniques developed to create and measure CQED states are now being applied to the development of quantum computers.
See also
*
Circuit quantum electrodynamics
Circuit quantum electrodynamics (circuit QED) provides a means of studying the fundamental interaction between light and matter (quantum optics). As in the field of cavity quantum electrodynamics, a single photon within a single mode cavity coher ...
*
Superconducting radio frequency
*
Dicke model Dicke is a surname. Notable people with the surname include:
* Amie Dicke (born 1978), Dutch artist
* Finn Dicke (born 2004), Dutch footballer
* Pien Dicke (born 1999), Dutch field hockey player
* Robert H. Dicke (1916–1997), American physicis ...
References
* Microwave wavelengths, atoms passing through cavity
* Optical wavelengths, atoms trapped
{{Quantum computing
Quantum information science