Quantum Information Processing, Vol. 3, Nos. 1–5, October 2004 (© 2004)
Quantum Information Processing in Cavity-QED
S. J. van Enk,
H. J. Kimble,
and H. Mabuchi
Received April 21, 2004; accepted May 20, 2004
We give a brief overview of cavity-QED and its roles in quantum information
science. In particular, we discuss setups in optical cavity-QED, where either atoms
serve as stationary qubits, or photons serve as ﬂying qubits.
KEY WORDS: Cavity QED; atom trapping & cooling; quantum computing;
PACS: 42.50.Pq; 03.67.Lx; 03.67.Hk; 32.80.Pj.
Cavity-QED provides an important paradigm for studying the controlled,
coherent coupling of optical and atomic qubits. The central phenome-
non of cavity-QED is strong coupling between the internal state of an
atom and the state of a single mode of the electromagnetic ﬁeld. In a
high-ﬁnesse microcavity, atoms and photons interact much more strongly
than they do in free space, and this enhancement can be used to imple-
ment quantum logic. For example, with a sufﬁciently good cavity it
becomes possible to observe nonlinear optical effects with just one pho-
ton per mode, and this provides a mechanism for controlled phase gates
between qubits encoded in the polarizations of single photon wave-pack-
Likewise, conditional mappings of the quantum state of ‘control’
and ‘target’ atoms trapped inside a cavity should be realizable by vir-
tue of their respective strong couplings to a common cavity eigenmode.
The direct atom–photon coupling itself enables quantum logic interactions
between qubit representations with very different physical properties, sug-
gesting applications in quantum communication where trapped atoms are
Bell Labs, Lucent Technologies and California Institute of Technology.
To whom correspondence should be addressed. E-mail: firstname.lastname@example.org
1570-0755/04/1000-0075/0 © 2004 Springer Science+Business Media, Inc.