Simultaneous Soft Pulses Applied at Nearby Frequencies

Steffen, Matthias; Vandersypen, L. M. K.; Chuang, Isaac L.

doi:10.1006/jmre.2000.2178

Cited by 38 publications

(48 citation statements)

References 16 publications

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“…For ideal inversion, the solid line should be −1 at the two frequencies, and the dashed line should be zero. From Steffen et al, 2000. ing to a dephasing time constant T 2 * ͑see Sec. V.A.2͒ of 1/͑20.5͒ = 0.32 s. In the course of long pulse sequences ͑of order 0.1-1 s͒, even the tiny remaining inhomogeneity would therefore have a large effect, so its effect must be reversed using refocusing sequences ͑Sec.…”

Section: Instrumental Errorsmentioning

confidence: 99%

NMR techniques for quantum control and computation

2005

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Fifty years of developments in nuclear magnetic resonance ͑NMR͒ have resulted in an unrivaled degree of control of the dynamics of coupled two-level quantum systems. This coherent control of nuclear spin dynamics has recently been taken to a new level, motivated by the interest in quantum information processing. NMR has been the workhorse for the experimental implementation of quantum protocols, allowing exquisite control of systems up to seven qubits in size. This article surveys and summarizes a broad variety of pulse control and tomographic techniques which have been developed for, and used in, NMR quantum computation. Many of these will be useful in other quantum systems now being considered for the implementation of quantum information processing tasks. CONTENTS

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Section: Instrumental Errorsmentioning

confidence: 99%

NMR techniques for quantum control and computation

2005

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“…For example, one deviation is due to transient Bloch-Siegert shifts, similar to NMR, 17,18 but these effects can be corrected using a method similar to the one described in Ref. 19.…”

Section: Shaped Pulsesmentioning

confidence: 99%

Accurate control of Josephson phase qubits

2003

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A quantum bit is a closed two-dimensional Hilbert space, but often experimental systems have three or more energy levels. In a Josephson phase qubit the energy differences between successive levels differ by only a few percent, and hence care must be taken to isolate the two desired levels from the remaining Hilbert space. Here we show via numerical simulations how to restrict operations to the qubit subspace of a three-level Josephson junction system requiring shorter time duration and suffering less error compared with traditional methods. This is achieved by employing amplitude modulated pulses as well as carefully designed sequences of square wave pulses. We also show that tunneling out of higher lying energy levels represents a significant source of decoherence that can be reduced by tuning the system to contain four or more energy levels.

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“…[18]. We note again the two d functions indicating the two different time orderings as in our discussion of Eq.…”

Section: Interaction Of a Spin-1/2 Particle With External Time-harmonmentioning

confidence: 97%

“…When introducing [18], the expression for the electromagnetic action functional reads [20], the action functional [19] can be written as…”

Section: The Feynman Propagatormentioning

confidence: 99%

Virtual photons in magnetic resonance

Engelke¹

2010

Concepts Magnetic Resonance

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Magnetic resonance often relies on a semi-classical picture in which the spin particles are submitted to quantum theory and the electromagnetic field is treated as a classical field. Although in many applications there are very good reasons to work within this theoretical framework, it appears worthwhile either for educational purposes, or for studies in magnetic resonance with microscopically small samples or very weak rf fields as well as for other applications that may seem exotic today, to ask how to gain a unified view when comparing the concepts and methods of quantum electrodynamics (QED) with those of classical electrodynamics commonly used in magnetic resonance. The present article attempts to develop such a unified view for electromagnetic interactions in magnetic resonance by focusing on the concept of virtual photon exchange based on the Feynman propagator technique and by exploring the cross links between basic aspects of ' 'semi-classical magnetic resonance' ' and the same basic aspects of magnetic resonance as seen through the frame of QED.

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Simultaneous Soft Pulses Applied at Nearby Frequencies

Cited by 38 publications

References 16 publications

NMR techniques for quantum control and computation

NMR techniques for quantum control and computation

Accurate control of Josephson phase qubits

Virtual photons in magnetic resonance

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