International Business Machines Corporation

Ralph G Devoe

John Allen Hoffnagle

Reinald Kallenbach

Richard G Brewer

Kenneth L Foster

Charles Thomas Rettner

Donald Stimson Bethune

William Paul Risk

Christian Kurtsiefer

An avalanche-type detector circuit includes an avalanche-type photon detector device, a coupling capacitor, a bias network, a first transmission line and a second transmission line. The coupling capacitor has a first terminal that is coupled to a first terminal of the avalanche-type photon detector device. A first terminal of the bias network is coupled to the first terminal of the avalanche-type photon detector device, while a second terminal of the bias network is coupled to a bias voltage so that the avalanche-type photon detector device is reverse biased. A first end of the first transmission line is coupled to a second terminal of the coupling capacitor, and second end of the first transmission line is terminated by an open-circuit termination. A first end of the second transmission line is coupled to a second terminal of the avalanche-type photon detector device. The second end of the second transmission line is terminated by a short-circuit termination. A bias pulse voltage V,is coupled to the second terminal of the coupling capacitor such that the bias pulse voltage reverse biases the avalanche-type photon detector device to be greater than a reverse breakdown voltage V,of the avalanche-type photon detector device during a duration of the bias pulse voltage V,. A round-trip propagation delay along the first transmission line is substantially equal to a round-trip propagation delay along the second transmission line.

System for gated detection of optical pulses containing a small number of photons using an avalanche photodiode

A parallel architecture of quantum logic gates and quantum communication channels is provided for a quantum computer, thereby achieving advantageous efficiency and computation speed. The architecture of the invention enables parallel memory operations on large quantum words, and permits the application, to the quantum case, of parallel algorithms for mathematical operations such as addition and multiplication. The invention also includes a novel apparatus for realizing parallel architecture using an array of miniature elliptical ion traps, with as many traps as there are bits in a quantum word. The ion trap array preferably uses an elliptical planar geometry, which can microfabricated by photolithography. Quantum information is transferred from one ion trap to another by either an optical coupling via a high finesse resonant cavity (photon coupling) or by electrostatic coupling of the ions' mechanical motion (phonon coupling).

Parallel architecture for quantum computers using ion trap arrays

An atomic clock system employs one of a family of ion trap configurations confining an ion in a potential well, such that a vibrational frequency confined ion may be measured accurately. The ion traps disclassed for use in such atomic clock systems include configurations of ring-shaped conductive members, or sheets of conductive material having circular holes therein. The trap apparatus further has a means to apply an RF field such that the resulting electric field being generated in a space defined by the conductive members has a characteristic of a substantially quadrupole field whereby a charged particle, being injected into the space, is confined in said field, maintaining a dynamic equilibrium condition.

Atomic clock employing ion trap of mono- or multi-planar geometry

An ion confinement, i.e., trap, apparatus comprises electrically conductive members, including concentric, coplanar rings or parallel sheets separated by dielectric spacers disposed on the outer edges of the sheets, each of the sheets having a circular hole, the circular holes being symmetrically aligned substantially along a common axis. The trap apparatus further has means for applying an RF potential to the conductive members, such that the resulting electric field being generated in the space defined by the conductive members has a characteristic of a substantially quadrupole field. A charged particle, being injected into the space, is confined in the field, maintaining a dynamic equilibrium condition.

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Palo Alto, CA, United States of America

Ralph G Devoe