Michael H Freedman

US Patent:

7250624, Jul 31, 2007

Filed:

Sep 23, 2005

Appl. No.:

11/233653

Inventors:

Michael H. Freedman - Redmond WA, US
Chetan V. Nayak - Santa Monica CA, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 29/06

US Classification:

257 12, 257 14, 257 9, 257 31, 257 39, 257E27005, 257E43003, 338 32

Abstract:

A quantum computer can only function stably if it can execute gates with extreme accuracy. “Topological protection” is a road to such accuracies. Quasi-particle interferometry is a tool for constructing topologically protected gates. Assuming the corrections of the Moore-Read Model for v= 5/2's FQHE (Nucl. Phys. B 360, 362 (1991)) we show how to manipulate the collective state of two e/4-charge anti-dots in order to switch said collective state from one carrying trivial SU(2) charge, |1>, to one carrying a fermionic SU(2) charge |ε>. This is a NOT gate on the {|1>, |ε>} qubit and is effected by braiding of an electrically charged quasi particle σ which carries an additional SU(2)-charge. Read-out is accomplished by σ-particle interferometry.

US Patent:

7321131, Jan 22, 2008

Filed:

Oct 7, 2005

Appl. No.:

11/245964

Inventors:

Michael H. Freedman - Redmond WA, US
Chetan V. Nayak - Santa Monica CA, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 29/06
H01L 21/00

US Classification:

257 9, 257 12, 257 14, 257E27005, 438800

Abstract:

Experiments suggest that the mathematically weakest non-abelian TQFT may be physically the most robust. Such TQFT's—the ν=5/2 FQHE state in particular—have discrete braid group representations, so one cannot build a universal quantum computer from these alone. Time tilted interferometry provides an extension of the computational power (to universal) within the context of topological protection. A known set of universal gates has been realized by topologically protected methods using “time-tilted interferometry” as an adjunct to the more familiar method of braiding quasi-particles. The method is “time-tilted interferometry by quasi-particles. ” The system is its use to construct the gates {g1, g2, g3}.

US Patent:

7394092, Jul 1, 2008

Filed:

Oct 6, 2006

Appl. No.:

11/544492

Inventors:

Michael H. Freedman - Redmond WA, US
Chetan V. Navak - Santa Monica CA, US
Sankar Das Sarma - Potomac MD, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 29/06

US Classification:

257 14, 257 11, 257 9, 257E43002, 257E43007, 338 32

Abstract:

A quantum computer can only function stably if it can execute gates with extreme accuracy. “Topological protection” is a road to such accuracies. Quasi-particle interferometry is a tool for constructing topologically protected gates. Assuming the corrections of the Moore-Read Model for ν=5/2's FQHE (Nucl. Phys. B 360, 362 (1991)) we show how to manipulate the collective state of two e/4-charge anti-dots in order to switch said collective state from one carrying trivial SU(2) charge, |1>, to one carrying a fermionic SU(2) charge |∈>. This is a NOT gate on the {|1>, |∈>} qubit and is effected by braiding of an electrically charged quasi particle a which carries an additional SU(2)-charge. Read-out is accomplished by σ-particle interferometry.

US Patent:

7427771, Sep 23, 2008

Filed:

Nov 19, 2007

Appl. No.:

11/942518

Inventors:

Michael H. Freedman - Redmond WA, US
Chetan V. Nayak - Santa Monica CA, US

Assignee:

Mircosoft Corporation - Redmond WA

International Classification:

H01L 29/06
H01L 21/00

US Classification:

257 9, 257 12, 257 14, 438800

Abstract:

Experiments suggest that the mathematically weakest non-abelian TQFT may be physically the most robust. Such TQFT's—the v=5/2 FQHE state in particular—have discrete braid group representations, so one cannot build a universal quantum computer from these alone. Time tilted interferometry provides an extension of the computational power (to universal) within the context of topological protection. A known set of universal gates has been realized by topologically protected methods using “time-tilted interferometry” as an adjunct to the more familiar method of braiding quasi-particles. The method is “time-tilted interferometry by quasi-particles. ” The system is its use to construct the gates {g1, g2, g3}.

US Patent:

7453162, Nov 18, 2008

Filed:

Aug 19, 2005

Appl. No.:

11/207508

Inventors:

Michael Freedman - Redmond WA, US
Chetan Nayak - Santa Monica CA, US
Kirill Shtengel - Seattle WA, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 23/58

US Classification:

257798, 706 33, 706 29, 257 31, 257 32, 257 33, 257 34, 257 35

Abstract:

Apparatus and methods for performing quantum computations are disclosed. Such apparatus and methods may include identifying a first quantum state of a lattice having a system of quasi-particles disposed thereon, moving the quasi-particles within the lattice according to at least one predefined rule, identifying a second quantum state of the lattice after the quasi-particles have been moved, and determining a computational result based on the second quantum state of the lattice.

US Patent:

7474010, Jan 6, 2009

Filed:

Feb 9, 2007

Appl. No.:

11/673213

Inventors:

Michael Freedman - Redmond WA, US
Chetan Nayak - Santa Monica CA, US
Kirill Shtengel - Seattle WA, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 23/58

US Classification:

257798, 257 31, 257 32, 257 33, 257 34, 257 35, 706 29, 706 33

Abstract:

Apparatus and methods for performing quantum computations are disclosed. Such apparatus and methods may include identifying a first quantum state of a lattice having a system of quasi-particles disposed thereon, moving the quasi-particles within the lattice according to at least one predefined rule, identifying a second quantum state of the lattice after the quasi-particles have been moved, and determining a computational result based on the second quantum state of the lattice.

US Patent:

7518138, Apr 14, 2009

Filed:

Aug 31, 2004

Appl. No.:

10/931082

Inventors:

Michael Freedman - Redmond WA, US
Chetan Nayak - Santa Monica CA, US
Kirill Shtengel - Seattle WA, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 29/06

US Classification:

257 9, 257E27005, 257798, 706 29, 706 33

Abstract:

Apparatus and methods for performing quantum computations are disclosed. Such apparatus and methods may include identifying a first quantum state of a lattice having a system of quasi-particles disposed thereon, moving the quasi-particles within the lattice according to at least one predefined rule, identifying a second quantum state of the lattice after the quasi-particles have been moved, and determining a computational result based on the second quantum state of the lattice. A topological quantum computer encodes information in the configurations of different braids. The computer physically weaves braids in the 2D+1 space-time of the lattice, and uses this braiding to carry out calculations. A pair of quasi-particles, such as non-abelian anyons, can be moved around each other in a braid-like path. The quasi-particles can be moved as a result of a magnetic or optical field being applied to them, for example.

US Patent:

7525202, Apr 28, 2009

Filed:

Aug 31, 2004

Appl. No.:

10/931083

Inventors:

Michael Freedman - Redmond WA, US
Chetan Nayak - Santa Monica CA, US
Kirill Shtengel - Seattle WA, US

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

H01L 23/58

US Classification:

257798, 257 31, 257 32, 257 33, 257 34, 257 35, 257E27001, 706 29, 706 33, 380 28, 380 29, 380 30, 380287

Abstract:

Apparatus and methods for performing quantum computations are disclosed. Such quantum computational systems may include quantum computers, quantum cryptography systems, quantum information processing systems, quantum storage media, and special purpose quantum simulators.