Office of Research, UC Riverside
Leonid Pryadko
Professor
Physics and Astronomy Dept
leonid@ucr.edu
(951) 827-5644


Collaborative Research: Statistical mechanics of non-local disordered models associated with quantum LDPC codes

AWARD NUMBER
007018-003
FUND NUMBER
21304
STATUS
Closed
AWARD TYPE
3-Grant
AWARD EXECUTION DATE
9/3/2014
BEGIN DATE
9/15/2014
END DATE
8/31/2017
AWARD AMOUNT
$15,390

Sponsor Information

SPONSOR AWARD NUMBER
PHY-1416578
SPONSOR
NATIONAL SCIENCE FOUNDATION
SPONSOR TYPE
Federal
FUNCTION
Organized Research
PROGRAM NAME

Proposal Information

PROPOSAL NUMBER
14050491
PROPOSAL TYPE
New
ACTIVITY TYPE
Basic Research

PI Information

PI
Pryadko, Leonid
PI TITLE
Other
PI DEPTARTMENT
Physics and Astronomy
PI COLLEGE/SCHOOL
College of Nat & Agr Sciences
CO PIs

Project Information

ABSTRACT

The main challenge for building a quantum computer is that quantum components are prone to error. Error correction can be used to overcome this challenge but it places stringent requirements on future quantum computer hardware. One promising method of quantum error correction is the so-called Quantum Low-Density-Parity-Check (LDPC) codes. If successful, using these codes a large quantum computer could in principle be built. Compared to other existing schemes, it would be much more efficient, requiring fewer redundant quantum bits, called qubits. Studying these codes will improve our understanding of the quantum theoretical problems related to quantum computation. This project will provide excellent opportunities for graduate students.

The award supports theoretical research on physics of non-local discrete and continuous statistical-mechanical models associated with quantum error correcting codes. An important feature of such codes is the existence of the decoding threshold, where a sufficiently large code can deal effectively with any noise level below the threshold, but not above it. Disordered spin models associated with decoding transition (these models have exact Wegner's self-duality), related models with large gauge groups associated with fault-tolerant decoding, as well as models with extensive ground state entropy, including U(1) gauge theories which generalize Wen's mutual Chern-Simons theory describing the ground state of Kitaev's toric code will be constructed and studied. Models associated with quantum LDPC codes are expected to be particularly interesting since their interaction terms involve a limited number of participating particles. The low-energy sectors of these models are expected to be dominated by non-trivial extended defects that generalize the notion of topological defects like domain walls, vortices, etc. New physics includes a phase transition driven by an extensive entropy of defect classes, coming from the exponentially large number of dimensions describing the original quantum code. Results will be relevant to several established fields of physics traditionally dealing with similar models: statistical mechanics of spin glasses, phase transition theory, etc., with potential applications extending to many other fields.
(Abstract from NSF)