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Search Publications by: Emanuel Knill (Fed)

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Displaying 126 - 150 of 182

Optimal Quantum Measurements of Expectation Values of Observables

January 24, 2007
Author(s)
Emanuel Knill, Gerardo Ortiz, Rolando Somma
Experimental characterizations of a quantum system involve the measurement of expectation values of observables for a preparable state |f> of the quantum system. Such expectation values can be measured by repeatedly preparing |f> and coupling the system to

Randomized Benchmarking of Quantum Gates

January 1, 2007
Author(s)
Emanuel Knill, D. Leibfried, R. Reichle, J. Britton, R. B. Blakestad, J. D. Jost, C. Langer, R Ozeri, Signe Seidelin, David J. Wineland
A key requirement for scalable quantum computing is that elementary quantum gates can be implemented with sufficiently low error. One method for determining the error behavior of a gate implementation is to perform process tomography. However, standard

Experimental purification of two-atom entanglement

October 19, 2006
Author(s)
Rainer Reichle, Dietrich G. Leibfried, Emanuel H. Knill, Joseph W. Britton, Brad R. Blakestad, John D. Jost, C. Langer, R Ozeri, Signe Seidelin, David J. Wineland
Entanglement is one of the most counterintuitive features of quantum mechanics. It is a necessary resource for quantum communication and quantum information processing. Entanglement established between different locations enables private communication and

Transport dynamics of single ions in segmented microstructured Paul trap arrays

August 4, 2006
Author(s)
Rainer Reichle, Dietrich G. Leibfried, Brad R. Blakestad, Joseph W. Britton, John D. Jost, Emanuel H. Knill, C. Langer, R Ozeri, Signe Seidelin, David J. Wineland
It was recently proposed to use small groups of trapped ions as qubit carriers in miniaturized electrode arrays that comprise a large number of individual trapping zones, between which ions could be moved. This approach might be scalable for quantum

Generalized Entanglement and Quantum Phase Transitions

July 30, 2006
Author(s)
Rolando Somma, Howard Barnum, Emanuel Knill, Gerardo Ortiz, Lorenza Viola
Effective visualizations can help researchers obtain a more complete understanding of high-level mathematical functions that arise in mathematics, statistics, physics, fluid dynamics and other fields of the mathematical and physical sciences. Accordingly

Trapped atomic ions and quantum information processing

July 16, 2006
Author(s)
David J. Wineland, Dietrich G. Leibfried, James C. Bergquist, Brad R. Blakestad, John J. Bollinger, Joseph W. Britton, J Chiaverini, Ryan Epstein, David Hume, Wayne M. Itano, John D. Jost, Emanuel H. Knill, Jeroen Koelemeij, C. Langer, R Ozeri, Rainer Reichle, Till P. Rosenband, Tobias Schaetz, Piet Schmidt, Signe Seidelin, Nobuyasu Shiga, Janus Wesenberg
The basic requirements for quantum computing and quantum simulation (Single- and multi-qubit gates, long memor times, etc.)have been demonstrated in separate experiments on trapped ions. Construction of a large-scale information processor will require

Recent experiments in trapped-ion quantum information processing at NIST

May 1, 2006
Author(s)
J Chiaverini, Matthew P. Barrett, Brad R. Blakestad, Joseph W. Britton, Wayne M. Itano, John D. Jost, Emanuel H. Knill, C. Langer, Dietrich G. Leibfried, R Ozeri, T Schaetz, David J. Wineland
Atomic ions confined in segmented trap arrays provide a system for quantum information processing. We report on the execution of two simple quantum algorithms, quantum error correction and the quantum Fourier transform, using this implementation. The

Recent experiments in trapped-ion quantum information processing at NIST

May 1, 2006
Author(s)
J Chiaverini, Murray D. Barrett, Brad R. Blakestad, Joseph W. Britton, Wayne M. Itano, John D. Jost, Emanuel H. Knill, C. Langer, Dietrich G. Leibfried, R Ozeri, Tobias Schaetz, David J. Wineland
Atomic ions confined in segmented trap arrays provide a system for quantum information processing. We report on the execution of two simple quantum algorithms, quantum error correction and the quantum Fourier transform, using this implementation. The

Error Analysis For Encoding a Qubit In An Oscillator

January 19, 2006
Author(s)
Scott Glancy, Emanuel Knill
In [5], Gottesman, Kitaev, and Preskill described a method to encode a qubit in the continuous Hilbert space of an oscillator's position and momentum variables. This encoding provides a natural error correction scheme which can correct errors due to small

Entanglement Purification of Any Stabilizer State

January 1, 2006
Author(s)
Scott Glancy, Emanuel Knill, Hilma M. Vasconcelos
We present a method for multipartite entanglement purification of any stabilizer state shared by several parties. In our protocol each party measures the stabilizer operators of a quantum error correcting code on his or her qubits. The parties exchange

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