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Search Publications by: Emanuel Knill (Fed)

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Displaying 76 - 93 of 93

Protected Realizations of Quantum Information

January 1, 2006
Author(s)
Emanuel H. Knill
There are two complementary approaches to realizing quantum information so that it is protected from a given set of error operators. Both involve encoding information by means of subsystems. Initialization-based error protection involves a quantum

Creation of a six-atom Schrodinger cat state

December 1, 2005
Author(s)
Dietrich G. Leibfried, Emanuel H. Knill, Signe Seidelin, Joseph W. Britton, Brad R. Blakestad, J Chiaverini, David Hume, Wayne M. Itano, John D. Jost, C. Langer, R Ozeri, Rainer Reichle, David J. Wineland
Among highly entangled states of multiple quantum systems, Schrödinger cat states are particularly useful. Cat states are equal superpositions of two maximally different quantum states. They are a fundamental resource in fault-tolerant quantum computing

Enhanced Quantum State Detection Efficiency Through Quantum Information Processing

October 1, 2005
Author(s)
T Schaetz, M D. Barrett, D. Leibfried, J. Britton, J. Chiaverini, W M. Itano, J. D. Jost, Emanuel Knill, C. Langer, David J. Wineland
The n-qubit concurrence canonical decomposition (CCD) is a generalization of the two-qubit canonical decomposition SU(4)=[SU(2) (x) SU(2)] ? [SU(2) (x) SU(2)], where ? is the commutative group which phases the maximally entangled Bell basis. A prequel

Quantum Computing with Realistically Noisy Devices

October 1, 2005
Author(s)
Emanuel H. Knill
There are quantum algorithms that can efficiently simulate quantum physics, factor large numbers and estimate integrals. As a result, quantum computers can solve otherwise intractable computational problems. One of the main problems of experimental quantum

Quantum Control, Quantum Information Processing, and Quantum-Limited Metrology With Trapped Ions

June 19, 2005
Author(s)
David J. Wineland, Dietrich G. Leibfried, Murray D. Barrett, A. Ben-Kish, James C. Bergquist, Brad R. Blakestad, John J. Bollinger, Joseph W. Britton, J Chiaverini, B. L. DeMarco, David Hume, Wayne M. Itano, M J. Jensen, John D. Jost, Emanuel H. Knill, Jeroen Koelemeij, C. Langer, Windell Oskay, R Ozeri, Rainer Reichle, Till P. Rosenband, Tobias Schaetz, Piet Schmidt, Signe Seidelin
We briefly discuss recent experiments on quantum informaiton processing using trapped ions at NIST. A central theme of this work has been to increase our capabilities in terms of quantum computing protocols, but we have also been interested in applying the

Implementation of the semiclassical quantum Fourier transform in a scalable system

May 13, 2005
Author(s)
J Chiaverini, Joseph W. Britton, Dietrich G. Leibfried, Emanuel H. Knill, Murray D. Barrett, Brad R. Blakestad, Wayne M. Itano, John D. Jost, C. Langer, R Ozeri, Tobias Schaetz, David J. Wineland
One of the most interesting future applications of quantum computers is Shor's factoring algorithm, which provides an exponential speedup compared to known classical algorithms. The crucial final step in Shor's algorithm is the quantum Fourier transform

Implementation of the Semiclassical Quantum Fourier Transform in a Scalable System

May 1, 2005
Author(s)
J. Chiaverini, J. Britton, D. Leibfried, Emanuel Knill, M D. Barrett, R. B. Blakestad, W M. Itano, J. D. Jost, C. Langer, R Ozeri, T Schaetz, D Britton, David J. Wineland
The n-qubit concurrence canonical decomposition (CCD) is a generalization of the two-qubit canonical decomposition SU(4)=[SU(2) (x) SU(2)] ? [SU(2) (x) SU(2)], where ? is the commutative group which phases the maximally entangled Bell basis. A prequel

Liquid-state NMR Simulations of Quantum Many-body Problems

April 1, 2005
Author(s)
C. Negrevergne, Rolando Somma, Gerardo Ortiz, Emanuel Knill, R. Laflamme
The n-qubit concurrence canonical decomposition (CCD) is a generalization of the two-qubit canonical decomposition SU(4)=[SU(2) (x) SU(2)] ? [SU(2) (x) SU(2)], where ? is the commutative group which phases the maximally entangled Bell basis. A prequel

Quantum Computing With Realistically Noisy Devices

March 3, 2005
Author(s)
Emanuel H. Knill
There are quantum algorithms that can efficiently simulate quantum physics, factor large numbers and estimate integrals. As a result, quantum computers can solve otherwise intractable computational problems. One of the main problems of experimental quantum

Quantum Computing with Very Noisy Devices

March 3, 2005
Author(s)
Emanuel H. Knill
There are quantum algorithms that can efficiently simulate quantum physics, factor large numbers and estimate integrals. As a result, quantum computers can solve otherwise intractable computational problems. One of the main problems of experimental quantum

Random decoupling schemes for quantum dynamical control and error suppression

February 18, 2005
Author(s)
Lorenza Viola, Emanuel Knill
We introduce a general control-theoretic setting for random dynamical decoupling, applicable to quantum , engineering of both closed-and open-system dynamics. The basic idea is to randomize the operations of the controller, by designing the control

Liquid state NMR simulations of quantum many-body problems

January 1, 2005
Author(s)
C. Negrevergne, Rolando Somma, Gerardo Ortiz, Emanuel Knill, R. Laflamme
Recently developed quantum algorithms suggest that in principle, quantum computers (QCs) can solve problems such as simulation of physical systems more efficiently than classical computers. As a small- scale demonstration of this capability of quantum

Realization of quantum error correction

December 2, 2004
Author(s)
J Chiaverini, Dietrich G. Leibfried, Tobias Schaetz, Murray D. Barrett, Brad R. Blakestad, Joseph W. Britton, Wayne M. Itano, John D. Jost, Emanuel H. Knill, C. Langer, R Ozeri, David J. Wineland
Scalable quantum computation and communication require error control to protect quantum information against unavoidable noise. Quantum error correction protects quantum information stored in two-level quantum systems (qubits) by rectifying errors with

Realization of Quantum Error Correction

December 1, 2004
Author(s)
J. Chiaverini, D. Leibfried, T Schaetz, M D. Barrett, R. B. Blakestad, J. Britton, W M. Itano, J. D. Jost, Emanuel Knill, C. Langer, R Ozeri, David J. Wineland
The n-qubit concurrence canonical decomposition (CCD) is a generalization of the two-qubit canonical decomposition SU(4)=[SU(2) (x) SU(2)] ? [SU(2) (x) SU(2)], where ? is the commutative group which phases the maximally entangled Bell basis. A prequel

Nature and Measure of Entanglement in Quantum Phase Transactions

October 1, 2004
Author(s)
Rolando Somma, Gerardo Ortiz, Howard Barnum, Emanuel Knill, Lorenza Viola
The n-qubit concurrence canonical decomposition (CCD) is a generalization of the two-qubit canonical decomposition SU(4)=[SU(2) (x) SU(2)] ? [SU(2) (x) SU(2)], where ? is the commutative group which phases the maximally entangled Bell basis. A prequel

Quantum information processing with trapped ions

July 25, 2004
Author(s)
Murray D. Barrett, Tobias Schaetz, J Chiaverini, Dietrich Leibfried, Joseph W. Britton, Wayne M. Itano, John D. Jost, Emanuel Knill, C. Langer, R Ozeri, David J. Wineland
We report experiments on the creation and manipulation ofmulti-particle entangled states of trapped atomic ions. The experiments reported here, quantum dense coding and quantum teleportation, constitute a significant step toward performing large-scale

Linear optics quantum computation

April 30, 2004
Author(s)
Emanuel H. Knill
Workshop presentation: Presentation is a high level review of technical and policy issues in quantum information.