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3 votes

How does an $\sqrt{X}$ error propagates through an $T$ gate?

If I understand correctly, you're saying that imagine your computation was supposed to have started in the state $|\psi\rangle$ and then had $T$ applied to it. But, instead, you actually started with $...
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2 votes
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What traces can be estimated in DQC1 (One clean qubit model), and how?

If you perform the circuit shown below, the density matrix of the first qubit before measurement reads: $$ \rho=\frac{1}{2}(\sigma_0+\frac{Re(Tr(U_n))}{2^n}\sigma_1+\frac{Im(Tr(U_n))}{2^n}\sigma_2)$$ ...
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2 votes

Qubit dephasing times

As you described, $T_2^*$ defines the decay time of coherence in a Ramsey experiment, while $T_2^{(echo)}$ and more generally $T_2^{(DD)}$ run a similar experiment but with intermediate refocusing ...
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0 votes

Fail to add amplitude damping error to NoiseModel

Actually, the amplitude damping error added to the NoiseModel successfully. The issue happens because the noisy gates are removed from your circuits before sending ...
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5 votes

Proven quantum advantage (in the algorithmic sense) without error correction (for specific algo, or noise models)

A photon based quantum computer named Jiuzhang in 2020 performed gaussian boson sampling (GBS) (Link to paper) of 76 photons.Researchers are interested in quantum algorithm for Boson sampling using ...
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1 vote

Proven quantum advantage (in the algorithmic sense) without error correction (for specific algo, or noise models)

This kind of asymptotic advantage strikes me as obviously impossible, or maybe even ill-defined, because without error correction the quantum computer can only do O(1) gates before your signal is ...
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