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Title:

Quantum Computing, Metrology, and Imaging

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Description:

Information science is entering into a new era in which certain subtleties of quantum mechanics enables large enhancements in computational efficiency and communication security. Naturally, precise control of quantum systems required for the implementation of quantum information processing protocols implies potential breakthoughs in other scienc...

Information science is entering into a new era in which certain subtleties of quantum mechanics enables large enhancements in computational efficiency and communication security. Naturally, precise control of quantum systems required for the implementation of quantum information processing protocols implies potential breakthoughs in other sciences and technologies. We discuss recent developments in quantum control in optical systems and their applications in metrology and imaging. Minimize

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The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2012-12-05

Source:

http://arxiv.org/pdf/quant-ph/0506150v1.pdf

http://arxiv.org/pdf/quant-ph/0506150v1.pdf Minimize

Document Type:

text

Language:

en

Subjects:

Quantum computing ; quantum entanglement ; optical interferometers ; High NOON states ; Heisenberg

Quantum computing ; quantum entanglement ; optical interferometers ; High NOON states ; Heisenberg Minimize

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Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

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Title:

One-atom maser: Non-separable atom pairs

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Description:

When a one-atom maser is operated in the standard way — excited, resonant two-level atoms traverse the resonator at random times — the emerging atoms are entangled with the cavity field. As a consequence, the results of measurements on different atoms tend to be correlated. We show that truly non-classical correlations can be found between two s...

When a one-atom maser is operated in the standard way — excited, resonant two-level atoms traverse the resonator at random times — the emerging atoms are entangled with the cavity field. As a consequence, the results of measurements on different atoms tend to be correlated. We show that truly non-classical correlations can be found between two successive atoms by studying the properties of the reduced state of such an atom pair. In particular, we calculate its degree of separability and find parameter ranges in which it is markedly less than unity. When a two-level atom and a photon mode undergo a Jaynes–Cummings interaction [1], they become entangled as a rule. Various aspects of atom-field entanglement of this kind have been studied in past years, whereby the emphasis is usually — but not always [2] — on the consequent atom-atom entanglement Minimize

Contributors:

The Pennsylvania State University CiteSeerX Archives

Year of Publication:

2012-12-05

Source:

http://arxiv.org/pdf/quant-ph/0209128v1.pdf

http://arxiv.org/pdf/quant-ph/0209128v1.pdf Minimize

Document Type:

text

Language:

en

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Metadata may be used without restrictions as long as the oai identifier remains attached to it.

Metadata may be used without restrictions as long as the oai identifier remains attached to it. Minimize

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Title:

Quantum state engineering and reconstruction in cavity QED: An analytical approach

Description:

The models of a strongly-driven micromaser and a one-atom laser are developed. Their analytical solutions are obtained by means of phase space techniques. It is shown how to exploit the model of a one-atom laser for simultaneous generation and monitoring of the decoherence of the atom-field "Schrödinger cat" states. The similar machinery applied...

The models of a strongly-driven micromaser and a one-atom laser are developed. Their analytical solutions are obtained by means of phase space techniques. It is shown how to exploit the model of a one-atom laser for simultaneous generation and monitoring of the decoherence of the atom-field "Schrödinger cat" states. The similar machinery applied to the problem of the generation of the maximally-entangled states of two atoms placed inside an optical cavity permits its analytical solution. The steady-state solution of the problem exhibits a structure in which the two-atom maximally-entangled state correlates with the vacuum state of the cavity. As a consequence, it is demonstrated that the atomic maximally-entangled state, depending on a coupling regime, can be produced via a single or a sequence of no-photon measurements. The question of the implementation of a quantum memory device using a dispersive interaction between the collective internal ground state of an atomic ensemble and two orthogonal modes of a cavity is addressed. The problem of quantum state reconstruction in the context of cavity quantum electrodynamics is considered. The optimal operational definition of the Wigner function of a cavity field is worked out. It is based on the Fresnel transform of the atomic invertion of a probe atom. The general integral transformation for the Wigner function reconstruction of a particle in an arbitrary symmetric potential is derived. Minimize

Publisher:

Ludwig-Maximilians-Universität München

Year of Publication:

2004-09-23

Document Type:

Dissertation ; NonPeerReviewed

Subjects:

Fakultät für Physik

Fakultät für Physik Minimize

DDC:

535 Light & infrared & ultraviolet phenomena *(computed)*

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http://edoc.ub.uni-muenchen.de/2638/

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Title:

Quantum description and properties of electrons emitted from pulsed nanotip electron sources

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We present a quantum calculation of the electron degeneracy for electron sources. We explore quantum interference of electrons in the temporal and spatial domain and demonstrate how it can be utilized to characterize a pulsed electron source. We estimate effects of Coulomb repulsion on two-electron interference and show that currently available ...

We present a quantum calculation of the electron degeneracy for electron sources. We explore quantum interference of electrons in the temporal and spatial domain and demonstrate how it can be utilized to characterize a pulsed electron source. We estimate effects of Coulomb repulsion on two-electron interference and show that currently available nano tip pulsed electron sources operate in the regime where the quantum nature of electrons can be made dominant. Minimize

Year of Publication:

2011-03-31

Document Type:

text

Subjects:

Quantum Physics

Quantum Physics Minimize

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Title:

An Observed-Data-Consistent Approach to the Assignment of Bit Values in a Quantum Random Number Generator

Description:

The majority of Quantum Random Number Generators (QRNG) are designed as converters of a continuous quantum random variable into a discrete classical random bit value. For the resulting random bit sequence to be minimally biased, the conversion process demands an experimenter to fully characterize the underlying quantum system and implement param...

The majority of Quantum Random Number Generators (QRNG) are designed as converters of a continuous quantum random variable into a discrete classical random bit value. For the resulting random bit sequence to be minimally biased, the conversion process demands an experimenter to fully characterize the underlying quantum system and implement parameter estimation routines. Here we show that conventional approaches to parameter estimation (such as e.g. {\it Maximum Likelihood Estimation}) used on a finite QRNG data sample without caution may introduce binning bias and lead to overestimation of the randomness of the QRNG output. To bypass these complications, we develop an alternative conversion approach based on the Bayesian statistical inference method. We illustrate our approach using experimental data from a time-of-arrival QRNG and numerically simulated data from a vacuum homodyning QRNG. Side-by-side comparison with the conventional conversion technique shows that our method provides an automatic on-line bias control and naturally bounds the best achievable QRNG bit rate for a given measurement record. ; Comment: submitted for publication Minimize

Year of Publication:

2014-04-23

Document Type:

text

Subjects:

Quantum Physics

Quantum Physics Minimize

DDC:

310 Collections of general statistics *(computed)*

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Title:

Emergent Quantum Jumps in a Nano-Electro-Mechanical System

Description:

We describe a nano-electromechnical system that exhibits the "retroactive" quantum jumps discovered by Mabuchi and Wiseman [Phys. Rev. Lett. 81, 4620 (1998)]. This system consists of a Cooper-pair box coupled to a nano-mechanical resonator, in which the latter is continuously monitored by a single-electron transistor or quantum point-contact. Fu...

We describe a nano-electromechnical system that exhibits the "retroactive" quantum jumps discovered by Mabuchi and Wiseman [Phys. Rev. Lett. 81, 4620 (1998)]. This system consists of a Cooper-pair box coupled to a nano-mechanical resonator, in which the latter is continuously monitored by a single-electron transistor or quantum point-contact. Further, we show that these kinds of jumps, and the jumps that emerge in a continuous quantum non-demolition measurement are one and the same phenomena. We also consider manipulating the jumps by applying feedback control to the Cooper-pair box. ; Comment: 7 pages, revtex4, 1 eps figure. v2 and v3: presentation altered, references added Minimize

Year of Publication:

2006-06-07

Document Type:

text

Subjects:

Quantum Physics ; Condensed Matter - Mesoscale and Nanoscale Physics

Quantum Physics ; Condensed Matter - Mesoscale and Nanoscale Physics Minimize

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Title:

Quantum Description and Properties of Electrons Emitted from Pulsed Nanotip Electron Sources

Description:

We present a quantum calculation of the electron degeneracy for electron sources. We explore quantum interference of electrons in the temporal and spatial domain and demonstrate how it can be utilized to characterize a pulsed electron source. We estimate effects of Coulomb repulsion on two-electron interference and show that currently available ...

We present a quantum calculation of the electron degeneracy for electron sources. We explore quantum interference of electrons in the temporal and spatial domain and demonstrate how it can be utilized to characterize a pulsed electron source. We estimate effects of Coulomb repulsion on two-electron interference and show that currently available nano tip pulsed electron sources operate in the regime where the quantum nature of electrons can be made dominant. Minimize

Publisher:

DigitalCommons@University of Nebraska - Lincoln

Year of Publication:

2011-01-01

Source:

Faculty Publications, Department of Physics and Astronomy

Faculty Publications, Department of Physics and Astronomy Minimize

Document Type:

text

Subjects:

Physics

Physics Minimize

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Title:

Continous Measurement of the Energy Eigenstates of a Nanomechanical Resonator without a Non-Demolition Probe

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We show that it is possible to perform a continuous measurement that continually projects a nano-resonator into its energy eigenstates by employing a linear coupling with a two-state system. This technique makes it possible to perform a measurement that exposes the quantum nature of the resonator by coupling it to a Cooper-pair Box and a superco...

We show that it is possible to perform a continuous measurement that continually projects a nano-resonator into its energy eigenstates by employing a linear coupling with a two-state system. This technique makes it possible to perform a measurement that exposes the quantum nature of the resonator by coupling it to a Cooper-pair Box and a superconducting transmission-line resonator. ; Comment: 4 pages, revtex4, two eps figures. v2: new results, much improved implementation; v4: published version, some terminology changed Minimize

Year of Publication:

2006-07-14

Document Type:

text

Subjects:

Quantum Physics ; Condensed Matter - Mesoscale and Nanoscale Physics

Quantum Physics ; Condensed Matter - Mesoscale and Nanoscale Physics Minimize

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Title:

Characterizing Entanglement Sources

Description:

We discuss how to characterize entanglement sources with finite sets of measurements. The measurements do not have to be tomographically complete, and may consist of POVMs rather than von Neumann measurements. Our method yields a probability that the source generates an entangled state as well as estimates of any desired calculable entanglement ...

We discuss how to characterize entanglement sources with finite sets of measurements. The measurements do not have to be tomographically complete, and may consist of POVMs rather than von Neumann measurements. Our method yields a probability that the source generates an entangled state as well as estimates of any desired calculable entanglement measures, including their error bars. We apply two criteria, namely Akaike's information criterion and the Bayesian information criterion, to compare and assess different models (with different numbers of parameters) describing entanglement-generating devices. We discuss differences between standard entanglement-verificaton methods and our present method of characterizing an entanglement source. ; Comment: This submission, together with the next one, supersedes arXiv:0806.4165 Minimize

Year of Publication:

2009-08-03

Document Type:

text

Subjects:

Quantum Physics

Quantum Physics Minimize

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Title:

Strengthened Bell Inequalities for Entanglement Verification

Description:

Bell inequalities were meant to test quantum mechanics vs local hidden variable models, but can also be used to verify entanglement. For entanglement verification purposes one assumes the validity of quantum mechanics as well as quantum descriptions of one's measurements. With the help of these assumptions it is possible to derive a strengthened...

Bell inequalities were meant to test quantum mechanics vs local hidden variable models, but can also be used to verify entanglement. For entanglement verification purposes one assumes the validity of quantum mechanics as well as quantum descriptions of one's measurements. With the help of these assumptions it is possible to derive a strengthened Bell inequality whose violation implies entanglement. We generalize known examples of such inequalities by relating the expectation value of the Bell operator to a particular quantitative measure of entanglement, namely the negativity. Moreover, we obtain statistics illustrating the fact that violating a given (strengthened or not) Bell inequality is a much more rare feat for a quantum state of two qubits than it is to be entangled. ; Comment: This submission, together with the previous one, supersedes arXiv:0806.4165 Minimize

Year of Publication:

2009-08-03

Document Type:

text

Subjects:

Quantum Physics

Quantum Physics Minimize

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