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Questions tagged [randomised-benchmarking]

The randomized benchmarking method yields estimates of the computationally relevant errors without relying on accurate state preparation and measurement. Since it involves long sequences of randomly chosen gates, it also verifies that error behavior is stable when used in long computations. (arXiv:0707.0963)

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Two definitions of the Clifford group and their relation

Clifford groups are used in at least 3 places I've encountered so far in QIP: A circuit that contains only Clifford operations, which are generated from CNOT, H and P, is sufficient for a wide ...
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5 votes
2 answers
398 views

Why does the twirl of a quantum channel give a depolarizing channel?

I would like to understand in detail why the twirl of a quantum channel gives depolarizing channel, which is the starting point of randomized benchmarking. To be self-contained, let me set up the ...
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What scheme should be used in case of applying non-Cliffords to estimate probability of success?

For Clifford gates (when performing randomized benchmarking and starting from ground state) the final state is always ground. It is acquired by applying at the end recovery gate, which transfers the ...
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2 votes
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How can I get fidelity of a gate from randomized benchmarking?

I found (page 33) the method of finding fidelity from fit by "interleaved and reference decay" according to the sequence fidelity formula: $$F_{ref}=Ap_{ref}^{m}+B,$$ where $p_{ref}^{m}$ is ...
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2 votes
1 answer
138 views

How do I pick a random Clifford operation in Stim?

I want to sample random n-qubit Clifford operations. How do I do that in Stim? (Self-answering because this was requested when the feature already existed)
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6 votes
0 answers
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Does Randomized Benchmarking characterize decoherence error?

In my understanding, Randomized Benchmarking (RB) generates a sequence of Clifford gates with different lengths and then characterizes the average error. Since RB is not sensitive to SPAM error, it ...
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1 vote
1 answer
76 views

Defining native gate dictionary in pyGSTi

In pyGSTi in order to construct Randomized Benchmarking circuits, we first need to define a pspec object that contains information about the number of qubits, basis ...
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5 votes
1 answer
90 views

What is the shortest-circuit-depth quantum-benchmarking algorithm?

An algorithm implementing a model whose results are known, and from the known results, the benchmarking of the device could be done. What is the currently known shortest circuit depth algorithm that ...
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6 votes
1 answer
117 views

Could a new benchmark of quantum processors Q-Score by Atos be more useful than quantum volume?

A few days ago, Atos company published new benchmark for quantum computers. The benchmark is called Q-Score and it is defined as follows: To provide a frame of reference for comparing performance ...
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0 votes
1 answer
187 views

What is the Clifford gates selection probability distribution used in the generation of randomized benchmarking circuits?

I've read that in standard randomized benchmarking implementations the random quantum circuits are generated through random gate selection from a uniformly distributed Clifford set of either 1 or 2-...
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1 vote
1 answer
56 views

Resources on randomized algorithms for analysis and design of quantum algorithms

Are there any good resources (online courses, books, websites, etc) to study randomized algorithms that would help with an specific scope on the analysis and design of quantum algorithms?
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1 vote
1 answer
258 views

How to split a Quantum Circuit on a barrier in Qiskit?

Let's say I have a QuantumCircuit with multiple barriers as shown in the visual below: How would I split up the ...
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4 votes
1 answer
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How to do randomised benchmarking for non-Clifford gates on Qiskit?

For my summer research internship I'm looking to randomized benchmark (RB) non-Clifford gates for a single qubit. Since I found out that Qiskit ignis allows for the RB of Clifford gates, naturally I ...
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2 votes
2 answers
212 views

What quantum volume is needed to represent a single logical qubit?

The quantum volume metric $V_Q$ is a proposed metric for quantifying and comparing the performance of quantum computers1. The quantum volume is defined as $$V_Q = \max_{n<N} \left(\min\left[n, d(n)...
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4 votes
1 answer
121 views

Using XOR games to benchmark quantum computers

In an answer to a previous question, What exactly are Quantum XOR Games?, ahelwer states: One application of xor games is self-testing: when running algorithms on an untrusted quantum computer, you ...
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7 votes
2 answers
386 views

Physical meaning of twirling in Randomized Benchmarking

I was reading papers on Randomized Benchmarking, such as this and this. (more specifically, equation 30 in the second paper) It appears to be some kind of averaging but I would like to have a more ...
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17 votes
1 answer
777 views

What is quantum t-design (intuitive understanding)?

I started reading about Randomized Benchmarking (this paper, arxiv version) and came across "unitary 2 design." After some googling, I found that the Clifford group being a unitary 2 design is a ...
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7 votes
1 answer
443 views

How to benchmark a quantum computer?

Using a simple puzzle game to benchmark quantum computers is the most clever approach I have seen so far. The author of the aforementioned article, James, makes a nice analogy to buying a laptop ("...
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3 votes
1 answer
174 views

Quantum algorithm to evaluate numbers in fast growing hierarchy

What quantum technologies and/or techniques (if any) could be used to evaluate the value of large numbers in the fast growing hierarchy such as Tree(3) or SCG(13)?
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18 votes
1 answer
769 views

Purpose of using Fidelity in Randomised Benchmarking

Often, when comparing two density matrices, $\rho$ and $\sigma$ (such as when $\rho$ is an experimental implementation of an ideal $\sigma$), the closeness of these two states is given by the quantum ...
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