International Workshop on Quantum LDPC Codes

Conference Date: 
Monday, July 14, 2014 (All day) to Wednesday, July 16, 2014 (All day)
Scientific Areas: 
Quantum Information
The subject of this workshop is at the leading edge of current research in Quantum Information, specifically in the field of quantum error correction.  Quantum LDPC codes is the only class of codes where a finite rate and a finite fault-tolerant error correction threshold are known to coexist.
This workshop will bring together researchers working on quantum LDPC codes, including the surface codes.  
Register for the workshop HERE.
Sponsorship for this conference has been provided by:

Sergei Bravyi, IBM Watson Research Center
Austin Fowler, University of California, Santa Barbara
Alexey Kovalev, University of Nebraska
Andrew Landahl, Sandia National Lab
*Hidetoshi Nishimori, Tokyo Institute of Technology
Robert Raussendorf, University of British Columbia
*Peter Shor, Massachusetts Institute of Technology
Barbara Terhal, IBM Watson Research Center
*Xiao-Gang Wen, Perimeter Institute

*Speakers to be confirmed

More speakers to be announced

Guest Speakers: Ground transportation arrangements will be made on your behalf and instructions sent prior to your arrival. If you need transportation while attending the conference, we offer suggestions below. If flying, we suggest that you book your flight to arrive at Toronto International Airport (YYZ) or the Region of Waterloo International Airport (YKF).

Boulevard Limousine (estimated travel time 1hr) The fare for Boulevard Limousine for one passenger is $118.00 to the Toronto Airport.  The fare for one passenger from the Toronto Airport to Waterloo is $133.00.  To make reservations, please visit their website or call 519-886-8090.

Airways Transit (estimated travel time 1hr) Airways Transit connects Toronto (Pearson), Hamilton (Munro), and Region of Waterloo International Airports with the Kitchener-Waterloo area by providing 24 hour shared ride door-to-door service. To make reservations online please visit their webiste of contact them by phone 24 hours: 519-886-2121.

0001 Toronto Cabs (estimated travel time 1hr)  Approximately $90.00 rate for one-way: Toronto International Airport to Waterloo. Call 416-809-5656. Waterloo Taxi (estimated travel time 1hr)  Fixed $76.50 rate for one-way: Waterloo to Toronto International Airport. Call 519-886-1200.  Note: One or more passengers can split this $90.00 flat rate.

Car Rentals Upon arrival in any of the terminals at Pearson International Airport there are a number of car rental agencies to choose from. Their booths are located on the arrivals level. The cost of a car rental is dependent upon the type of vehicle you would like and the length of the stay. 

Driving Directions 

  • From the airport, follow signs for Highway 427 South/Highway 401.  
  • Continue to follow signs for Highway 401 West - London.  
  • Proceed West on Highway 401.  
  • Exit Highway 401 at Highway 8 West.  
  • Take exit 278 (Highway 8 West) and follow 8 West for 5 km to Highway 85, towards Highway 7 East. 
  • Proceed on Highway 85 for 5 km to Bridgeport Road exit. Turn right at the off-ramp, traveling west.  
  • Follow Bridgeport Road for 2 km into downtown Waterloo.  
  • Bridgeport is a four-lane one-way road. It becomes Caroline Street at Albert Street. Continue straight ahead.  
  • Travel forward another 200 metres, but ease over into the right-hand lane. As you go down a hill and around a curve, look for the green Perimeter Institute sign on the right hand side. The parking lot entrance is just after the sign (past the historic grist mill that sits on the edge of Silver Lake).  
  • Turn right into the PI parking lot entrance.

*Guest Speakers: Accommodation arrangements will be made on your behalf and instructions sent prior to your arrival. If you need accommodations while attending the conference, we offer suggestions for lodging below.

Waterloo Hotel 2 King Street North Waterloo, ON N2J 2W7 Phone: 519-885-2626 Distance from PI: 400 m

Waterloo Inn 475 King Street North Waterloo, ON N2J 2Z5 Reservation line: 1-800-361-4708 Reservation e-mail: Distance from PI: 3 km

Walper Terrace Hotel 1 King Street West Kitchener, ON N2G 1A1 Phone: 519-745-4321 Distance from PI: 4 km

Courtyard by Marriott 50 Benjamin Road East St. Jacobs, ON N2V 2J9 Phone: 519-884-9295 Distance from PI: 5.6 km

International Workshop on Quantum LDPC Codes

Perimeter Institute, Waterloo, Ontario, July 14 to July 16, 2014

The purpose of the workshop is to bring together researchers working on quantum LDPC codes, including the surface codes. All aspects related to such codes are of interest, including code constructions, syndrome decoding algorithms, bounds on the parameters, fault-tolerant processing, thresholds with different noise models, possible implementations, etc.

What are the quantum LDPC codes and why are they interesting?

Quantum low density parity-check codes are also known as quantum sparse-graph codes. Technically, these are just stabilizer codes, but with stabilizer generators which involve only a few qubits each compared to the number of qubits used in the code. Such codes are most often degenerate: some errors have trivial effect and do not require any correction. Compared to general quantum codes, with a quantum LDPC code, each quantum measurement involves fewer qubits, measurements can be done in parallel, and also the classical processing could potentially be enormously simplified.

The most famous family of quantum sparse-graph codes is Kitaev's toric construction: it has a relatively high threshold for scalable quantum computation, around 1% total error probability per quantum gate or a qubit measurement, and only local gates are needed. One disadvantage is that all toric and related surface codes encode very few qubits (in technical terms, they have asymptotically zero rate); thus they require many redundant physical qubits.

Finite-rate quantum LDPC codes are also possible. Several large families of such codes are known. With these, fewer redundant qubits may be necessary to build a useful quantum computer.

Quantum sparse graph codes are commonly called quantum LDPC codes by analogy with the classical low density parity-check codes. These latter codes have fast and efficient (capacity-approaching) decoders. Over the last ten years classical LDPC codes have become a significant component of industrial standards for satellite communications, Wi-Fi, and gigabit ethernet, to name a few. The success of classical LDPC codes is the reason for some of the interest in the quantum LDPC codes.

Why is this workshop needed now?

Over the last five years, several families of finite-rate quantum LDPC codes with explicitly known parameters have been constructed, and the existence of a finite error-correction threshold established. These are the key milestones indicating that such codes could be a viable option for coherence protection in quantum computers of the future.

However, there is still a lot to learn about quantum LDPC codes. Here are just a few of the questions: Are there general decoding algorithms nearly as good as the belief propagation algorithm which works so well for classical LDPC codes? Are there specific bounds on parameters of quantum LDPC codes? What are the most efficient protocols for fault-tolerant logical operations acting on the encoded qubits? 

Scientific Organizers:

  • Daniel Gottesman, Perimeter Institute
  • David Poulin, University of Sherbrooke
  • John Preskill, California Institute of Technology
  • Leonid Pryadko, University of California, Riverside
  • Jean-Pierre Tillich, INRIA