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Single T gate in a Clifford circuit drives transition to universal entanglement spectrum statistics

by Shiyu Zhou, Zhi-Cheng Yang, Alioscia Hamma, Claudio Chamon

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Submission summary

Authors (as registered SciPost users): Alioscia Hamma · Shiyu Zhou
Submission information
Preprint Link: scipost_202004_00048v3  (pdf)
Date accepted: 2020-12-09
Date submitted: 2020-12-02 17:18
Submitted by: Zhou, Shiyu
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Quantum Physics
Approach: Theoretical


Clifford circuits are insufficient for universal quantum computation or creating $t$-designs with $t\ge 4$. While the entanglement entropy is not a telltale of this insufficiency, the entanglement spectrum is: the entanglement levels are Poisson-distributed for circuits restricted to the Clifford gate-set, while the levels follow Wigner-Dyson statistics when universal gates are used. In this paper we show, using finite-size scaling analysis of different measures of level spacing statistics, that in the thermodynamic limit, inserting a single T $(\pi/8)$ gate in the middle of a random Clifford circuit is sufficient to alter the entanglement spectrum from a Poisson to a Wigner-Dyson distribution.

Author comments upon resubmission

We thank Referee 1 for recommending publication of our manuscript. We address comments from Referee 2 in detail in the reply.

Published as SciPost Phys. 9, 087 (2020)

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