Classical simulation of quantum computation, the Gottesman-Knill theorem, and slightly beyond

  • Authors:
  • Maarten Van Den Nes

  • Affiliations:
  • Max-Planck-Institut für Quantenoptik, Garching, Germany

  • Venue:
  • Quantum Information & Computation
  • Year:
  • 2010

Quantified Score

Hi-index 0.00

Visualization

Abstract

We study classical simulation of quantum computation, taking the Gottesman-Knilltheorem as a starting point. We show how each Clifford circuit can be reduced to anequivalent, manifestly simulatable circuit (normal form). This provides a simple proofof the Gottesman-Knill theorem without resorting to stabilizer techniques. The normalform highlights why Clifford circuits have such limited computational power in spiteof their high entangling power. At the same time, the normal form shows how theclassical simulation of Clifford circuits fits into the standard way of embedding classicalcomputation into the quantum circuit model. This leads to simple extensions of Cliffordcircuits which are classically simulatable. These circuits can be efficiently simulated byclassical sampling ("weak simulation") even though the problem of exactly computingthe outcomes of measurements for these circuits ("strong simulation") is proved to be#P-complete-thus showing that there is a separation between weak and strong classicalsimulation of quantum computation.