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Prospects for Quantum Coherent Computation Using Superconducting Electronics
 IEEE Trans. Appl. Supercond
, 1997
"... We discuss the prospects and challenges for implementing a quantum computer using superconducting electronics. It appears that Josephson junction devices operating at milliKelvin temperatures can achieve a quantum dephasing time of milliseconds, allowing quantum coherent computations of 10 10 or ..."
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Cited by 29 (9 self)
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We discuss the prospects and challenges for implementing a quantum computer using superconducting electronics. It appears that Josephson junction devices operating at milliKelvin temperatures can achieve a quantum dephasing time of milliseconds, allowing quantum coherent computations of 10 10 or more steps. This figure of merit is comparable to that of atomic systems currently being studied for quantum computation. I. INTRODUCTION In quantum coherent computation information is coded not just as "1" and "0" but also as coherent superpositions of the "1" and "0" states of a quantum mechanical two state system. Recent experiments from atomic and optical physics have demonstrated the creation and manipulation of such quantum mechanical bits, socalled `qubits' [1][3], and consideration is being given to the prospects for constructing simple quantum computers. In this paper we will discuss the prospects for a superconducting electronics implementation of quantum computation. The great ...
Solving Highly Constrained Search Problems with Quantum Computers
 Journal of Artificial Intelligence Research
, 1999
"... A previously developed quantum search algorithm for solving 1SAT problems in a single step is generalized to apply to a range of highly constrained kSAT problems. We identify a bound on the number of clauses in satisfiability problems for which the generalized algorithm can find a solution in a co ..."
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Cited by 10 (0 self)
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A previously developed quantum search algorithm for solving 1SAT problems in a single step is generalized to apply to a range of highly constrained kSAT problems. We identify a bound on the number of clauses in satisfiability problems for which the generalized algorithm can find a solution in a constant number of steps as the number of variables increases. This performance contrasts with the linear growth in the number of steps required by the best classical algorithms, and the exponential number required by classical and quantum methods that ignore the problem structure. In some cases, the algorithm can also guarantee that insoluble problems in fact have no solutions, unlike previously proposed quantum search algorithms. 1. Introduction Quantum computers (Benioff, 1982; Bernstein & Vazirani, 1993; Deutsch, 1985, 1989; DiVincenzo, 1995; Feynman, 1986; Lloyd, 1993) offer a new approach to combinatorial search problems (Garey & Johnson, 1979) with quantum parallelism, i.e., the abilit...
The Search for the Quantum ‘SpeedUp’—Between the
, 2006
"... In 1981 Richard Feynman conjectured that any classical simulation of quantum dynamical evolution could only be done inefficiently, incurring an exponential slowdown in the simulation time. This pessimism marked the dawn of quantum computing, a research field which a generation later has become one o ..."
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In 1981 Richard Feynman conjectured that any classical simulation of quantum dynamical evolution could only be done inefficiently, incurring an exponential slowdown in the simulation time. This pessimism marked the dawn of quantum computing, a research field which a generation later has become one of the most fascinating domains of quantum mechanics. Today, while experimentalists are struggling with the technologies needed for the construction of a scalable quantum computer, theoreticians are still looking for algorithms that can establish the superiority of quantum computers over their classical counterparts. Embarrassingly, so far only one algorithm has been discovered that is provably more efficient than any known classical algorithm. In this paper I shall offer a possible reason for the lack of efficient quantum algorithms, which stems from the features of quantum mechanics itself. Inconclusive as it is, the skepticism I raise with respect to the putative power of quantum computers serves to elucidate a major interpretative issue in the foundations of quantum mechanics, and may also have constructive implications for the future of quantum algorithms design.
B OUNDS OF C OMPUTING AFTER THE TRANSISTOR, THE QUBIT?
"... Attention is increasingly focused on quantum computing as a path to the continued rapid growth of informationprocessing technology. But like other physical circuitry, quantum computers must face the uncomfortable fact that manmade objects aren’t exact reproductions of idealized devices and aren’t ..."
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Attention is increasingly focused on quantum computing as a path to the continued rapid growth of informationprocessing technology. But like other physical circuitry, quantum computers must face the uncomfortable fact that manmade objects aren’t exact reproductions of idealized devices and aren’t invariably perfectly reproducible. The consequences of this imperfection threaten the future of quantum computing.