Pseudorandom circuits from Clifford-plus-Tgates

Abstract

We explore the implementation of pseudo-random single-qubit rotations and multi-qubit pseudo-random circuits constructed only from Clifford gates and the T-gate, a phase rotation of pi/4. Such a gate set would be appropriate for computations performed in a fault tolerant setting. For single-qubit rotations the distribution of parameters found for unitaries constructed from Clifford plus T quickly approaches that of random rotations and require significantly fewer gates than the construction of arbitrary single-qubit rotations. For Clifford plus T pseudo-random circuits we find an exponential convergence to a random matrix element distribution and a Gaussian convergence to the higher order moments of the matrix element distribution. These convergence rates are insensitive to the number of qubits.