Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.

The organizing committee includes Malcolm Boshier (P-21), Diego Dalvit (T-4), Michael Di Rosa (C-PCS), Sebastian Deffner (T-4 & CNLS), Changhyun Ryu (P-21) , Nikolai Sinitsyn (T-4), Rolando Somma (T-4), Christopher Ticknor (T-1), and Wojciech Zurek (T-4).

For more information, or to nominate a speaker, contact Sebastian Deffner.

To add your name to the Quantum Lunch email list, contact Kacy Hopwood.

Thursday May 5, 2016
12:30 PM - 2:00 PM

Speaker: Jon Yard (Microsoft Research)

Technical Host: Rolando Somma

TOPIC: Compiling quantum gates

Abstract
Fault-tolerant quantum computers will compute by applying a sequence of elementary unitary operations, or gates, to an error-protected subspace. While algorithms are typically expressed over arbitrary local gates, there is unfortunately no known theory that can correct errors for a continuous set of quantum gates. However, theory does support the fault-tolerant construction of various finite gate sets, which, in some cases, generate circuits that can approximate arbitrary gates to any desired precision.

In this talk, I will present joint work with Kliuchnikov, Bocharov and Roetteler on a framework for approximating arbitrary qubit unitaries over a very general but natural class of gate sets. These gate sets are derived from the theory of integral quaternions over number fields and generate S-arithmetic subgroups of SU(2). In this framework, the complexity of a unitary is algebraically encoded in the length of a corresponding quaternion. The algorithm achieves epsilon-approximations with circuits of length O(log(1/epsilon)), which is optimal up to constant factors.