John D Howell

US Patent:

20040042512, Mar 4, 2004

Filed:

Aug 27, 2002

Appl. No.:

10/228285

Inventors:

Antia Lamas-Linares - Oxford, GB
John Howell - New York NY, US
Dik Bouwmeester - Oxford, GB

International Classification:

H01S003/10

US Classification:

372/021000

Abstract:

A method and apparatus for enhancing the production of polarisation-entangled multiphoton states from a laser pumped parametric down-converting crystal. The pump beam and initial down-converted photons are returned by retro mirrors, in phase to the down-converting crystal where they stimulate the emission of further polarisation-entangled states. The efficiency of the process is increased by including in the path of the returning down-converted photons a crystal of the same substance and thickness as the down-converting crystal to provide spatial and temporal walk-off compensation. Further, the phase of the returning pump beam is adjusted and optimised by control of the retro-mirror while monitoring the rate of production of polarisation-entangled photon pairs. Maximising the rate of production of photon pairs also maximises the rate of production of higher-order states, such as four-photon states.

US Patent:

49575244, Sep 18, 1990

Filed:

May 15, 1989

Appl. No.:

7/351807

Inventors:

Ravindra F. Pahade - Getzville NY
John H. Ziemer - Grand Island NY
John K. Howell - Tonawanda NY

Assignee:

Union Carbide Corporation - Danbury CT

International Classification:

F25J 302

US Classification:

62 18

Abstract:

A cryogenic rectification method wherein liquid from a top condenser-reboiler is cleaned of higher boiling impurities by passage through an adsorbent bed and returned to the condenser-reboiler, wherein the flow back to the condenser-reboiler is driven by combination with density-reducing vapor.

US Patent:

59015780, May 11, 1999

Filed:

May 18, 1998

Appl. No.:

9/080305

Inventors:

Kenneth Kai Wong - Amherst NY
Michael James Lockett - Grand Island NY
Dante Patrick Bonaquist - Grand Island NY
Vijayaraghavan Srinivasan - Williamsville NY
John Keller Howell - Tonawanda NY

Assignee:

Praxair Technology, Inc. - Danbury CT

International Classification:

F25J3/00

US Classification:

62646

Abstract:

A cryogenic rectification system wherein a product boiler is incorporated into the primary heat exchanger without encountering boiling to dryness problems wherein liquid from the cryogenic rectification plant is processed in a phase separator upstream of the product boiler, and fluid from the product boiler is passed into the phase separator prior to recovery.