# Tag Info

Accepted

### Is the "Quantum Volume" a fair metric for future, elaborate, high value quantum computations?

Quantum volume is likely only useful as a metric for small noisy computers. It’s impossible to invent any single-number metric that’s ideal for all tasks. Even with classical computers, metrics such ...
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### Is the "Quantum Volume" a fair metric for future, elaborate, high value quantum computations?

As a start, you might want to look at https://arxiv.org/abs/1605.03590, which lays out conservative (i.e., high) qubit and gate requirements for a meaningful quantum chemistry calculation under some ...
• 470
Accepted

### What use cases are there for 127 qubit QPUs?

I think that the main reason behind is to tackle technical difficulties connected with building huge number of qubits. Having hundred of qubits brings about issues with interconnection, connections to ...
• 14.6k
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### Is there a way to decompose a quantum circuit into layers?

You can decompose a quantum circuit into layers using DAGCircuit.layers() method: ...
• 10.8k
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### Can we calculate the quantum volume of a classical computer?

The log quantum volume of Quirk ( https://algassert.com/quirk ) is 16, because it has a maximum of 16 qubits and can easily do the ~200 gates that are part of the test circuit. The slowest part will ...
• 38.4k
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### How to calculate the quantum Volume?

Here is an example of using Qiskit to benchmark quantum devices using the Quantum Volume metric. It generates the quantum volume model circuits, compiles them, runs them, and fits the result to find ...
• 1,632
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### How quantum volume relates to the number of qubits

If $N$ is the number of QV layers that a quantum processor can successfully run (and therefore the number of qubits of the QV circuit), the QV is actually given by $2^N$, so a QV of $32=2^5$ means $5$ ...
Accepted

### Why is the quantum volume vastly greater than the number of qubits squared?

It is not an error. Under the subsection IBM's modified definition, they define the quantum volume as: $\log_2 V_Q = \arg\max_{n \le N} \{\min [n, d(n)]\}$ That is, if you take the minimum of the ...
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### How can I use the quantum volume to design the scale of my experiment?

You can't. The quantum volume is supposed to be an average measure of the quality of the quantum computer - it doesn't tell you anything on how good it will perform on solving a certain problem. (It ...
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### What quantum volume is needed to represent a single logical qubit?

Quantum volume is a bad metric for this purpose. For example, suppose you have a ten thousand by ten thousand grid of qubits with a gate error rate of 1 in one thousand. The quantum volume of this ...
• 38.4k
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### Could a new benchmark of quantum processors Q-Score by Atos be more useful than quantum volume?

(3) is a solid objection. I'm not sure what specifically is meant by "number of variables within a problem that a quantum technology can optimize" but we can use the results of [1] (Fig 4) ...
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### What quantum volume is needed to represent a single logical qubit?

The Quantum Volume is a benchmark for near term, noisy quantum systems. Indeed, like other random unitary benchmarks, you need to be able to sample the ideal distribution. This distribution comes from ...
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### QV circuits fail to execute in real devices

As per Qiskit's release notes, under "IBM Q Provider 0.12.0"[1] qiskit.providers.ibmq.IBMQBackend.run() method now takes one or more ...
• 10.8k

### QV circuits fail to execute in real devices

By doing some error tracking, you'll find that TypeError: 'QasmQobj' object is not iterable` was raised from ...
• 2,503

### What use cases are there for 127 qubit QPUs?

This paper may be of interest in regards to this question; we were able to execute QAOA circuits using all 127 qubits of ibm_washington (and the computation was not complete noise, due to the short ...

### Is there a straightforward way to calculate the quantum volume for simple systems?

I believe the calculation steps are quite complex to give a simple formula or even to follow it by hand. Maybe this medium article and the cited paper gives you a better general understanding. As you ...
• 508
1 vote

### Can we somehow relate quantum volume with the total number of gates present in a circuit which the machine can succesfully run without large errors

Quantum volume is a metric designed to quantify the performance and capabilities of a quantum computer. It encompasses various factors like gate fidelity, connectivity, coherence time, and others to ...
1 vote

### Is there something like error-suppression codes?

A recently posted preprint proposed a method that the authors named distance-scaled zero noise extrapolation (DSZNE), which combines the application of surface codes (QEC) with zero noise ...
1 vote
Accepted

### Is it possible to set quantum volume in IBM Quantum simulator?

Bear in mind that if you operate on a subset of $n$ qubits, then your QV is at most $2^n$. Hence the answer below assumes that you'd like to experiment with a simulator that has $n$ qubits but some \$...
• 632
1 vote

### Is there a straightforward way to calculate the quantum volume for simple systems?

To put in simple words, the quantum volume tells a maximal dimension of state space (Hilbert space) you can simulate on a quantum computer sucessfully. For example, quantum volume 64 means that you ...
• 14.6k

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