Feynman’s model of a quantum computer provides an example of a continuous-time quantum walk. Its clocking mechanism is an excitation of a basically linear chain of spins with occasional controlled jumps which allow for motion on a planar graph. The spreading of the wave packet poses limitations on the probability of ever completing the s elementary steps of a computation: an additional amount of storage space δ is needed in order to achieve an assigned completion probability. In this note we study the END instruction, viewed as a measurement of the position of the clocking excitation: a π-pulse indefinitely freezes the contents of the input/output register, with a probability depending only on the ratio δ/s.

Quantum timing and synchronization problems / D. de Falco, D. Tamascelli. - In: INTERNATIONAL JOURNAL OF MODERN PHYSICS B. - ISSN 0217-9792. - 18:4-5(2004 Feb 20), pp. 623-631. [10.1142/S0217979204024240]

Quantum timing and synchronization problems

D. de Falco
Primo
;
D. Tamascelli
Ultimo
2004

Abstract

Feynman’s model of a quantum computer provides an example of a continuous-time quantum walk. Its clocking mechanism is an excitation of a basically linear chain of spins with occasional controlled jumps which allow for motion on a planar graph. The spreading of the wave packet poses limitations on the probability of ever completing the s elementary steps of a computation: an additional amount of storage space δ is needed in order to achieve an assigned completion probability. In this note we study the END instruction, viewed as a measurement of the position of the clocking excitation: a π-pulse indefinitely freezes the contents of the input/output register, with a probability depending only on the ratio δ/s.
π-pulse trap; Continuous-time quantum walk; Grover's algorithm; Quantum END problem; Quantum subroutines; Telomeric chain
Settore MAT/06 - Probabilita' e Statistica Matematica
20-feb-2004
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/34863
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