Quantum Information Processing, Vol. 6, No. 4, August 2007 (© 2007)
Information Free Quantum Bus for Generating
Simon J. Devitt,
Andrew D. Greentree,
and Lloyd C. L. Hollenberg
Received May 24, 2007; accepted June 12, 2007; Published online: September 6, 2007
Efﬁcient generation of spatially delocalised entangled states is at the heart of
quantum information science. Generally, ﬂying qubits are proposed for long range
entangling interactions, however here we introduce a bus-mediated alternative for
this task. Our scheme permits efﬁcient and ﬂexible generation of determinis-
tic two-qubit operator measurements and has links to the important concepts of
mode-entanglement and repeat-until-success protocols. Importantly, unlike ﬂying
qubit protocols, our bus particle never contains information about the individual
quantum states of the particles, hence is information-free.
KEY WORDS: quantum computing; adiabatic transport; parity gates; multi-
partite entanglement; entangled states; bus particles; information-free.
PACS: 03.67.Hk; 03.67.Mn; 03.67.Lx.
Recent research into quantum information and computation has not
only spawned a number of architecture proposals for quantum compu-
tation (QC), but also proposals for useful technologies based on smal-
ler, entangled quantum systems. Quantum key distribution,
and the improvement of frequency standards using entan-
are strong examples of how highly entangled states can be
exploited to build novel devices: The incorporation of such entangled-state
protocols with existing micro- and nano-scale fabrication is an enormous
opportunity for the semiconductor industry.
Centre for Quantum Computer Technology, School of Physics, University of Melbourne,
Melbourne, VIC 3010, Australia.
To whom correspondence should be addressed. E-mail: firstname.lastname@example.org
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