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76
Toward An Architecture For Quantum Programming
, 2003
"... It is becoming increasingly clear that, if a useful device for quantum computation will ever be built, it will be embodied by a classical computing machine with control over a truly quantum subsystem, this apparatus performing a mixture of classical and quantum computation. This paper investigates ..."
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It is becoming increasingly clear that, if a useful device for quantum computation will ever be built, it will be embodied by a classical computing machine with control over a truly quantum subsystem, this apparatus performing a mixture of classical and quantum computation. This paper investigates a possible approach to the problem of programming such machines: a template high level quantum language is presented which complements a generic general purpose classical language with a set of quantum primitives.
Quantum information with rydberg atoms
 Rev. Mod. Phys
, 2010
"... Rydberg atoms with principal quantum number n1 have exaggerated atomic properties including dipoledipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom qubits. ..."
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Cited by 47 (2 self)
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Rydberg atoms with principal quantum number n1 have exaggerated atomic properties including dipoledipole interactions that scale as n4 and radiative lifetimes that scale as n3. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom qubits. The availability of a strong longrange interaction that can be coherently turned on and off is an enabling resource for a wide range of quantum information tasks stretching far beyond the original gate proposal. Rydberg enabled capabilities include longrange twoqubit gates, collective encoding of multiqubit registers, implementation of robust lightatom quantum interfaces, and the potential for simulating quantum manybody physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydbergmediated quantum information processing.
A Quantum Logic Array Microarchitecture: Scalable Quantum Data Movement and Computation
 Proceedings of the 38th International Symposium on Microarchitecture MICRO38
, 2005
"... Recent experimental advances have demonstrated technologies capable of supporting scalable quantum computation. A critical next step is how to put those technologies together into a scalable, faulttolerant system that is also feasible. We propose a Quantum Logic Array (QLA) microarchitecture that f ..."
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Cited by 29 (3 self)
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Recent experimental advances have demonstrated technologies capable of supporting scalable quantum computation. A critical next step is how to put those technologies together into a scalable, faulttolerant system that is also feasible. We propose a Quantum Logic Array (QLA) microarchitecture that forms the foundation of such a system. The QLA focuses on the communication resources necessary to efficiently support faulttolerant computations. We leverage the extensive groundwork in quantum error correction theory and provide analysis that shows that our system is both asymptotically and empirically fault tolerant. Specifically, we use the QLA to implement a hierarchical, arraybased design and a logarithmic expense quantumteleportation communication protocol. Our goal is to overcome the primary scalability challenges of reliability, communication, and quantum resource distribution that plague current proposals for largescale quantum computing. Our work complements recent work by Balenseifer et al [1], which studies the software tool chain necessary to simplify development of quantum applications; here we focus on modeling a fullscale optimized microarchitecture for scalable computing. 1.
Violation of Bell’s inequality in Josephson phase qubits, Nature 461
, 2009
"... 1 The measurement process plays an awkward role in quantum mechanics, as measurement forces a system to "choose" between possible outcomes in a fundamentally unpredictable manner. Hidden classical processes have therefore been considered as possibly predetermining measurement outcomes wh ..."
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Cited by 21 (4 self)
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1 The measurement process plays an awkward role in quantum mechanics, as measurement forces a system to "choose" between possible outcomes in a fundamentally unpredictable manner. Hidden classical processes have therefore been considered as possibly predetermining measurement outcomes while preserving their statistical distributions In classical physics, deterministic laws provide a complete description for the evolution of a physical system. Quantum physics purports to provide an equally complete description, but the measurement process involves additional premises, and measurement outcomes are intrinsically uncertain. When performing measurements on entangled particles, however, the unpredictability of measurement is combined with very strong correlations between measurements on the individual particles, leading to the apparently paradoxical thought experiments developed by Einstein, Podolsky, and Rosen [12]. The CHSH protocol [10] describes one such experiment, with a statistical test to distinguish classical predetermination from quantum theory. This protocol uses a pair of spin The Bell signal S is then defined as Classical (predetermined) outcomes result in a Bell signal S ≤ 2, while quantum mechanics permits a larger signal S ≤ 2 √ 2 = 2.828, for the appropriate measurement axes. Completely random outcomes result in S = 0. An experiment returns a Bell violation if S > 2, and thus indicates quantum entanglement. The derivation of the limit S ≤ 2 is based on two assumptions, which, if not met, provide loopholes that, in principle, allow an experiment to return a Bell violation even for a classically predetermined process. The first loophole is called the "detection loophole" The second loophole, the "locality/causality loophole", applies when the spin measure particles, which are entangled via an electromagnetic resonator The Josephson phase qubit, as described previously In previous experiments two qubits were entangled in a Bell singlet through capacitive coupling and 93.4% are within a few percent of the predicted maximum of 96.6% Although the transfer of qubit entanglement through the resonator slightly complicates the control sequence, as shown in Since the CHSH version of the Bell inequality is not based on any assumptions about the entangled state or the choice of measurement axes, we use search optimization of all relevant parameters in the sequence to maximize S. We find that this search always converges to a violation with S > 2 using sequence parameters that make physical sense (see Supplementary Information). For example, the measurement axes are close to those expected for maximum violation, with the angle between a and a (b and b ) close to 90 • , and the relative inplane angle between a and b close to 45 • . However the plane of (a, a ) is rotated by an arbitrary azimuthal angle from (b, b ) as a phase shift between the states 01 and 10 is produced by the differing qubit frequencies and the tuning pulses that bring the qubits on resonance with the resonator (see With optimal parameters, we measure a Bell signal with S = 2.0732 ± 0.0003, which corresponds to a violation by 244 standard deviations. This value is obtained from an average over 34.1 million runs of the sequence. We estimate that with perfect measurement fidelities the Bell signal would be S = 2.355 (see Supplementary Information). Given that this result is only a single number, it is important to perform verification experiments to check for errors. After all, turning off the measurement electronics gives P 00 = 1 and S = 2. In [26] that slightly overestimates the effects of dephasing, and our maximization of S accounts for small asymmetries in qubit parameters, which are not included in the simulations. Another comparison of fidelity is shown in With the difference between experiment and theory after four full swap operations (arrow (2)) less than 1%, we believe the errors due to the entanglement operation, corresponding to 2qubit errors, are less than 1%. This is not unexpected as prior entangling experiments between a qubit and a resonator gave high fidelities In conclusion, we have measured a violation of the CHSH Bell inequality in a macroscopic solid state quantum system that closes the detection loophole. We note that successfully performing this measurement requires the simultaneous optimization of a number of qubit performance benchmarks, which together form most of what are known as the DiVincenzo criteria for a quantum computational architecture
A quantum computing primer for operator theorists
 Linear Algebra Appl
, 2005
"... Abstract. This is an exposition of some of the aspects of quantum computation and quantum information that have connections with operator theory. After a brief introduction, we discuss quantum algorithms. We outline basic properties of quantum channels, or equivalently, completely positive trace pre ..."
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Cited by 15 (3 self)
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Abstract. This is an exposition of some of the aspects of quantum computation and quantum information that have connections with operator theory. After a brief introduction, we discuss quantum algorithms. We outline basic properties of quantum channels, or equivalently, completely positive trace preserving maps. The main theorems for quantum error detection and correction are presented and we conclude with a description of a particular passive method of quantum error correction. 1.
Hybrid quantum circuits: Superconducting circuits interacting
, 2013
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Trapped Atoms in Cavity QED for Quantum Optics and Quantum Information
, 2004
"... My first thanks go to Jeff Kimble for providing me the opportunity to work in this exciting field, and to be a part of his outstanding research group. Needless to say, his tireless efforts have played an instrumental role in the progress we’ve made these past few years. Beyond this direct contributi ..."
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My first thanks go to Jeff Kimble for providing me the opportunity to work in this exciting field, and to be a part of his outstanding research group. Needless to say, his tireless efforts have played an instrumental role in the progress we’ve made these past few years. Beyond this direct contribution, I have learned immeasurable amounts from him, not only in terms of scientific skills both theoretical and experimental. I also owe a debt of gratitude to my colleagues from Lab 11, where all the work in this thesis was done. This list begins with David Vernooy and Jun Ye, who constructed the heart of the experiment, which continues to beat to this day. Postdoctoral fellows Dan StamperKurn and HannsChristoph Nägerl provided excellent leadership, and I learned a great deal from both of them. Special thanks also go to Joe Buck, with whom our first real breakthroughs were achieved. Joe was a great friend and colleague throughout both the good times and the months before that weren’t quite as pleasant. Alex Kuzmich provided several important scientific contributions to our lab, which are greatly appreciated. Andreea Boca, David Boozer and Russ Miller have been tremendous friends and coworkers, and a separate paragraph of gratitude could be written about each of them. Amazing progress already being made as of this writing is a testament to the fact that the lab could not be
Physical limits of heatbath algorithmic cooling
, 2007
"... Simultaneous nearcertain preparation of qubits (quantum bits) in their ground states is a key hurdle in quantum computing proposals as varied as liquidstate NMR and ion traps. “Closedsystem ” cooling mechanisms are of limited applicability due to the need for a continual supply of ancillas for f ..."
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Cited by 6 (2 self)
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Simultaneous nearcertain preparation of qubits (quantum bits) in their ground states is a key hurdle in quantum computing proposals as varied as liquidstate NMR and ion traps. “Closedsystem ” cooling mechanisms are of limited applicability due to the need for a continual supply of ancillas for fault tolerance and to the high initial temperatures of some systems. “Opensystem” mechanisms are therefore required. We describe a new, efficient initialization procedure for such open systems. With this procedure, an nqubit device that is originally maximally mixed, but is in contact with a heat bath of bias ε ≫ 2 −n, can be almost perfectly initialized. This performance is optimal due to a newly discovered threshold effect: For bias ε ≪ 2 −n no cooling procedure can, even in principle (running indefinitely without any decoherence), significantly initialize even a single qubit.
Toward Quantum Computational Agents
 Computational Autonomy. Lecture Notes in Computer Science Series
, 2004
"... Abstract. In this chapter, we provide some first thoughts on, and preliminary answers to the question how intelligent software agents could take most advantage of the potential of quantum computation and communication, once practical quantum computers become available in foreseeable future. In parti ..."
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Cited by 4 (3 self)
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Abstract. In this chapter, we provide some first thoughts on, and preliminary answers to the question how intelligent software agents could take most advantage of the potential of quantum computation and communication, once practical quantum computers become available in foreseeable future. In particular, we discuss the question whether the adoption of quantum computational and communication means will affect the autonomy of individual and systems of agents. We show that the ability of quantum computing agents to perform certain computational tasks more efficient than classically computing agents is at the cost of limited selfautonomy, due to nonlocal effects of quantum entanglement. 1