1,385 research outputs found
The Quantum Frontier
The success of the abstract model of computation, in terms of bits, logical
operations, programming language constructs, and the like, makes it easy to
forget that computation is a physical process. Our cherished notions of
computation and information are grounded in classical mechanics, but the
physics underlying our world is quantum. In the early 80s researchers began to
ask how computation would change if we adopted a quantum mechanical, instead of
a classical mechanical, view of computation. Slowly, a new picture of
computation arose, one that gave rise to a variety of faster algorithms, novel
cryptographic mechanisms, and alternative methods of communication. Small
quantum information processing devices have been built, and efforts are
underway to build larger ones. Even apart from the existence of these devices,
the quantum view on information processing has provided significant insight
into the nature of computation and information, and a deeper understanding of
the physics of our universe and its connections with computation.
We start by describing aspects of quantum mechanics that are at the heart of
a quantum view of information processing. We give our own idiosyncratic view of
a number of these topics in the hopes of correcting common misconceptions and
highlighting aspects that are often overlooked. A number of the phenomena
described were initially viewed as oddities of quantum mechanics. It was
quantum information processing, first quantum cryptography and then, more
dramatically, quantum computing, that turned the tables and showed that these
oddities could be put to practical effect. It is these application we describe
next. We conclude with a section describing some of the many questions left for
future work, especially the mysteries surrounding where the power of quantum
information ultimately comes from.Comment: Invited book chapter for Computation for Humanity - Information
Technology to Advance Society to be published by CRC Press. Concepts
clarified and style made more uniform in version 2. Many thanks to the
referees for their suggestions for improvement
Quantum cryptography: key distribution and beyond
Uniquely among the sciences, quantum cryptography has driven both
foundational research as well as practical real-life applications. We review
the progress of quantum cryptography in the last decade, covering quantum key
distribution and other applications.Comment: It's a review on quantum cryptography and it is not restricted to QK
Basic concepts in quantum computation
Section headings: 1 Qubits, gates and networks 2 Quantum arithmetic and
function evaluations 3 Algorithms and their complexity 4 From interferometers
to computers 5 The first quantum algorithms 6 Quantum search 7 Optimal phase
estimation 8 Periodicity and quantum factoring 9 Cryptography 10 Conditional
quantum dynamics 11 Decoherence and recoherence 12 Concluding remarksComment: 37 pages, lectures given at les Houches Summer School on "Coherent
Matter Waves", July-August 199
Experimental Quantum Private Queries with linear optics
The Quantum Private Query is a quantum cryptographic protocol to recover
information from a database, preserving both user and data privacy: the user
can test whether someone has retained information on which query was asked, and
the database provider can test the quantity of information released. Here we
introduce a new variant Quantum Private Query algorithm which admits a simple
linear optical implementation: it employs the photon's momentum (or time slot)
as address qubits and its polarization as bus qubit. A proof-of-principle
experimental realization is implemented.Comment: 4 pages, 2 figure
Towards practical quantum position verification
We discuss protocols for quantum position verification schemes based on the
standard quantum cryptographic assumption that a tagging device can keep
classical data secure [Kent, 2011]. Our schemes use a classical key replenished
by quantum key distribution. The position verification requires no quantum
communication or quantum information processing. The security of classical data
makes the schemes secure against non-local spoofing attacks that apply to
schemes that do not use secure tags. The schemes are practical with current
technology and allow for errors and losses. We describe how a
proof-of-principle demonstration might be carried out
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