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1500 questions
12
votes
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How does the invertibility of a quantum map reflect on its Kraus operators?
Consider a quantum map $\Phi\in\mathrm T(\mathcal X)$, that is, a linear operator $\Phi:\mathrm{Lin}(\mathcal X)\to\mathrm{Lin}(\mathcal X)$ for some finite-dimensional complex vector spaces $\mathcal X$.
In the specific case in which $\Phi$ is also…
glS
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How many qubits would be needed to do boson sampling in Qiskit?
In December 2020, there was this claim of quantum advantage/supremacy by a team of UST China using Gaussian boson sampling. Here is the paper and here is an explanatory news article in Nature. To get an idea of how that works, I wanted to try to…
Mauricio
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Are true Projective Measurements possible experimentally?
I have heard various talks at my institution from experimentalists (who all happened to be working on superconducting qubits) that the textbook idea of true "Projective" measurement is not what happens in real-life experiments. Each time I asked…
Dr. T. Q. Bit
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Active improving of nanodiamond surfaces for NV centers?
This question is related (and complementary) to "Passive improving of nanodiamond surfaces for NV centers?".
Nitrogen-Vacancy centers (NVs) have astonishing quantum properties, which make them interesting as potential hardware both for quantum…
agaitaarino
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12
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Simulating Clifford + few-T circuits
I want to simulate large stabilizer circuits (H/S/CNOT/MEASURE/feedforward) with a small number of T gates mixed in. How can I do this in a way that scales exponentially only in the number of T gates? Are there existing implementations?
Craig Gidney
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Are circuits with more than 1000 gates common?
I have seen circuits with 30 qubits and around 500 gates. Also circuits with 32 qubits and 6000 gates. Are circuits with more than 1000 gates common in quantum computing? Are there many quantum algorithms that require more than 1000 gates? How…
Alejandro Arcila
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What is the difference between "Shot-Noise-Limit" and "Standard Quantum Limit"?
It seems that in a lot of papers in the field of quantum metrology, there are two terms Shot-Noise-Limit and Standard Quantum Limit which are frequently referred to. What's the difference between them, because it seems they all refer to the limit…
narip
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12
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Characteristics of the IBM quantum computer
On the IBM Quantum Composer website, there are characteristics of qubit computers. For example, ibmq_16_melbourne.
But there is no description anywhere of what:
T1(us),
T2(us),
Frequency (GHz),
Readout assignment error,
Prob meas0 prep1,
Prob meas1…
alexhak
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How to check if a quantum circuit can be constructed for a given matrix representation?
Let's say I have a matrix representation, e.g.
$$
\begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & 0 & 1 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & 0 & 1
\end{pmatrix}.
$$
How can I determine whether a quantum circuit can be constructed given said matrix representation?…
Dorijan Cirkveni
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How to store qubits while preserving Heisenberg's uncertainty principle?
I know that qubits are represented by quantum particles (for example photons) and that their state is given by one property (for example spin).
My question is about the quantum memory: how are the qubits stored in a quantum computer. I suppose we…
User that hates AI
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Transversal logical gate for Stabilizer (or at least Steane code)
I know that for Steane code, we can implement transversally some gates like cNOT, Hadamard and Pauli.
What I am looking for is a resource in which it is explained why implementing those gate give rise to the good logical operation.
If this is a…
Marco Fellous-Asiani
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12
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What kinds of ions do trapped ion quantum computers use?
Trapped ion quantum computers are among the most promising approaches to achieve large-scale quantum computation.
The general idea is to encode the qubits into the electronic states of each ion, and then control the ions via electromagnetic…
glS
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How can quantum decoherence be managed?
I've stumbled myself upon this article on Wikipedia, which says:
Decoherence can be viewed as the loss of information from a system into the environment (often modeled as a heat bath), since every system is loosely coupled with the energetic state…
user609
12
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How are elementary quantum gates realised?
When expressing computations in terms of a quantum circuit, one makes use of gates, that is, (typically) unitary evolutions.
In some sense, these are rather mysterious objects, in that they perform "magic" discrete operations on the states.
They are…
glS
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Can quantum computers handle 'big' data?
While there are many interesting questions that a computer can solve with barely any data (such as factorization, which requires "only" a single integer), most real-world applications, such as machine learning or AI, will require large amounts of…
Discrete lizard
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