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Top Questions

4 votes
2 answers
1k views

A necessary and sufficient condition for the existence of a nontrivial square root in Shor's algorithm

4 votes
2 answers
2k views

How to properly understand Born's rule as written in the Feynman Lectures?

9 votes
2 answers
479 views

Are these gate sets proven to be not universal?

4 votes
2 answers
325 views

How to convert a partially entangled state into maximally entangled using SLOCC

1 vote
1 answer
815 views

Why can't Grover's algorithm apparently solve this simple situation?

2 votes
1 answer
197 views

Finding the eigenvalues of a qutrit state

3 votes
2 answers
126 views

Equivalence of circuits in measurement-based QC

5 votes
2 answers
97 views

Decomposition of a $4 \times 4$ unitary matrix

4 votes
1 answer
200 views

How to characterize the extreme points of the set of CPTP maps?

4 votes
1 answer
123 views

Bug in stim HERALDED_PAULI_CHANNEL_1?

3 votes
1 answer
119 views

Is possible to write a separable state as a finite or countable infinite sum of product states?

2 votes
1 answer
155 views

Problem with eigenvalue evaluation algorithm application on matrix $U$

2 votes
2 answers
119 views

Preparation of logical state with qLDPC code

4 votes
1 answer
150 views

Questions on multi-controlled Toffolis and their implementation in Qiskit

5 votes
1 answer
107 views

Question about Nielson & Chuang Problem 9.2

2 votes
1 answer
79 views

Classical capacity of quantum channel - Holevo quantity vs accessible information of a channel

2 votes
1 answer
124 views

Finding the "dual" basis of an overcomplete basis for Quantum State Tomography

1 vote
2 answers
95 views

Is there a way to perform Zero Noise Extrapolation with qiskit without using the runtime service?

3 votes
1 answer
90 views

What is the difference between quantum teleportation and quantum entanglement with dense coding?

1 vote
1 answer
70 views

Does quantum mutual information encompass information only about quantum correlations, or does it encompass both classical and quantum correlations?

1 vote
1 answer
114 views

Derivation of Choi-Jamiolkowski isomorphism

2 votes
1 answer
114 views

study quantum hardware

2 votes
1 answer
110 views

If_test() - Dynamic Circuits in qiskit

3 votes
1 answer
82 views

Why is the operator $M_a |x\rangle= |a \cdot x \pmod{N} \rangle $ unitary?

3 votes
1 answer
100 views

How much complexity is required to implement $\text{C$_\Pi$NOT}$ gate?

2 votes
1 answer
94 views
+50

Number of logical cycles to implement $R_Z(\theta)$ gates in lattice surgery: why isn't it the number of layers $\times$ the $T$-count in $R_Z$?

3 votes
1 answer
73 views

is a mixed states really a statistical mixture?

2 votes
1 answer
68 views

Quantum homomorphic encryption with a classical verifier - clarifying the setting?

2 votes
1 answer
67 views

Is a process matrix of rank $1$ unique?

1 vote
2 answers
51 views

Does the $\text{CNOT}$ gate activate if the control qubit is $-|1⟩?$

1 vote
1 answer
104 views

How do I apply Amplitude Amplification for following state?

4 votes
1 answer
80 views

What is known about the size of the spectral gap of unital quantum channels?

3 votes
1 answer
79 views

What is the difference between classical-quantum and completely classical states?

1 vote
1 answer
61 views

How to convert stim encoder circuit to a parity check matrix?

2 votes
1 answer
60 views

What does "lift" mean in the Lifted Product (LP) Code?

3 votes
1 answer
94 views

Hadamard Gate on Cluster States

1 vote
1 answer
91 views

Problem with the mathematical definition of the eigenvalue algorithm on a specific exercise

3 votes
1 answer
54 views

Which single-qubit mixed states work for magic state distillation?

1 vote
2 answers
53 views

creating a generalised Bell state with gates

1 vote
2 answers
68 views

Why $\sqrt{\rho} = P \sqrt{\rho}$ in the proof of quantum error correction conditions in Nielsen & Chuang?

2 votes
1 answer
65 views

Constructing a two 3-qubit state involving either X, Y or Z rotation gate

2 votes
2 answers
64 views

Conditioned gates with multiple classical bits

2 votes
1 answer
64 views

How do I write a stim diagram to a file?

2 votes
1 answer
82 views

How to measure in $\sigma_x$ basis in Qiskit? [duplicate]

1 vote
1 answer
80 views

How to properly generate circuit measurement results from detector error model

2 votes
1 answer
77 views

How does this measurement in the Hadamard basis look like?

2 votes
0 answers
96 views

Mutual information of shared state is larger than expectation values

0 votes
1 answer
57 views

Quantum Error Correction on a hexagonal lattice


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