Quantum Computing Stack Exchange
Quantum Computing Stack Exchange

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Is there a convention for denoting $Y$ eigenstates?

Two common shorthands for eigenstates of the $Z$ operator are $\{|0\rangle,|1\rangle\}$ and $\{|1\rangle,|-1\rangle\}$, where in the first case we have $Z|z\rangle=(-1)^z|z\rangle$ and in the second case we have $Z|z\rangle=z|z\rangle$. The common…
Jahan Claes
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How would a Quantum Computer (network) perform loophole-free Bell tests?

In a simple form, Bell's theorem states that: No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics. Bell developed a series of inequalities to provide specific experimental examples to…
agaitaarino
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Adiabatic Quantum Computing vs Adiabatic Quantum Optimization vs Quantum Annealing

I am aware that of the difference of Adiabatic Quantum Computing (AQC) and Quantum Annealing (QA) as explained here. However, another term which came up in some papers was Adiabatic Quantum Optimization (AQO). Where does AQO fit in among AQC and…
ArcaneArrowX
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Gradient boosting akin to XGBoost using a quantum device

I am currently trying to implement a boosting algorithm akin to XGBoost with a quantum device. The reason is that I want to make use of a quantum device to train weak classifiers. However, as far as I know, the current quantum device can only be…
QuanFinance
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Can we synthesize quantum many body systems with quantum computers quickly in the general case?

Quantum computing can be used to efficiently simulate quantum many-body systems. Solving such a problem is classically hard because its complexity grows exponentially with the problem size (roughly with the degree of freedoms), which is an inherent…
peterh
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Does superdense coding allow to double the information capacity of a set of qubits?

I read the basic introductory information about qubits on Wikipedia: There are two possible outcomes for the measurement of a qubit—usually 0 and 1, like a bit. The difference is that whereas the state of a bit is either 0 or 1, the state of a…
Kaspar Siricenko
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Use of the term "dimension" in this description of Simon's algorithm?

In Kaye, Laflamme and Mosca (2007) pg106 they write the following (in the context of Simon's algorithm): ...where $S=\{\mathbf{0},\mathbf{s}\}$ is a $2$-dimensional vector space spanned by $\mathbf{s}$. this is not the only place I have seen this…
Quantum spaghettification
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What do we mean by parity of qubits?

I am currently reading "Quantum Computation and Quantum Information" by Nielsen and Chuang. In the section about Quantum Simulation, they give an illustrative example (section 4.7.3), which I don't quite understand: Suppose we have the Hamiltonian…
brzepkowski
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Intuition for Shor code failure probability

Consider the 9 qubit Shor code. This can detect and correct arbitrary single qubit errors, but if there are 2 or more single qubit errors before a correction round, the correction will fail. (In the sense that it won't reproduce the original logical…
anon1802
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Shor's algorithm caveats when $a^{r/2} =-1 \mod N$

For an integer, $N$, to be factorised, with $a$ (uniformly) chosen at random between $1$ and $N$, with $r$ the order of $a\mod N$ (that is, the smallest $r$ with $a^r\equiv 1\mod N$): Why is that in Shor's algorithm we have to discard the scenario…
Tech Solver
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Dependency of architecture on hardware

How much of a role does the type of hardware used to implement the building blocks (like qubits, the circuits, the communication channels,quantum RAM etc.) have to play when designing the architecture for a full scale quantum computer? My own…
ak_nama
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Which is the highest number factorized by QC in a non-specific experiment?

Since the original experimental contribution using the Shor's factoring algorithm to factorize the integer 15 some experiments have been performed in order to calculate the largest factorized number. But most of the experiments are particularly…
SalvaCardona
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What is the difference between amplitude amplification, amplitude estimation, and phase estimation?

I'm confused about the difference among Amplitude amplification (AA) , phase estimation (PE), and Amplitude Estimation. I thought I understood AA and PE somewhat but when I heard the amplitude estimation and the circuit looked so similar to phase…
John Parker
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Are SU($n$) operations enough for quantum computation?

Usually we want a quantum computer that can perform all foreseeable unitary operations U($n$). A quantum processor that can naturally perform at least 2 rotation operators $R_k(\theta)=\exp(-i\theta\sigma_k/2)$, where $\sigma_k$ are the Pauli…
Mauricio
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Apply readout error mitigation to mid-circuit measurement

I'm trying to construct a quantum circuit with 3 mid-circuit measurements, here's an example: qrz = QuantumRegister(2,'q') crz = ClassicalRegister(3,'c') qc = QuantumCircuit(qrz,crz) for i in range (3): qc.append(qc1(...),[0,1]). # qc1 is…
ZR-
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