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Quantum Computing

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3 votes
2 answers
2k views

What is the fastest quantum computational algorithm by which quantum computer speed up than classic one?

XL _At_Here_There
  • 209
4 votes
2 answers
1k views

Is quantum teleportation fully secure (in principle)?

benrg
  • 703
4 votes
2 answers
245 views

Necessity of decoding in fault-tolerant quantum computation

Craig Gidney
  • 24.8k
5 votes
2 answers
147 views

How to intuitively understand why $T$ gate can't be implemented transversally?

Craig Gidney
  • 24.8k
8 votes
2 answers
254 views

Non-entangling two-qubit gates

Adam Zalcman
  • 14.8k
3 votes
1 answer
239 views

is cirq suitable for simulation of quantum error correction?

Craig Gidney
  • 24.8k
5 votes
2 answers
59 views

Reasonable Circuit Depth

Craig Gidney
  • 24.8k
3 votes
2 answers
166 views

Are continuous probability distributions over quantum channels possible?

glS♦
  • 19.6k
4 votes
1 answer
101 views

How to represent a statevector in Dirac notation form using Qiskit?

Cody Wang
  • 588
2 votes
2 answers
272 views

Why is an X gate a quantum coin flip?

Ohad
  • 1,237
2 votes
2 answers
156 views

Matrix representation of SWAP on two qubit registers?

R.W
  • 1,997
2 votes
2 answers
242 views

Is there any resource in which you can find some information about how much money is needed to start making any kind of qubit?

user253751
  • 121
0 votes
2 answers
144 views

CNOT gate an elementary example of a single qubit quantum operation

Ohad
  • 1,237
2 votes
1 answer
125 views

What does the centered dot notation mean in the expression $|+\rangle|+\rangle\otimes(\cdot)$?

banercat
  • 37
1 vote
1 answer
81 views

How can I represent the completely mixed state as $\frac I2=\frac14(\rho+X\rho X+Y\rho Y+Z\rho Z)$?

glS♦
  • 19.6k
2 votes
1 answer
91 views

Why can any quantum channel be represented as a matrix?

narip
  • 2,607
1 vote
3 answers
68 views

Is the resolution of a physical qubit's probability limited?

Craig Gidney
  • 24.8k
5 votes
2 answers
52 views

What's the most efficient decomposition in terms of T-count of the 4-qubit Toffoli with 1 ancilla?

Craig Gidney
  • 24.8k
2 votes
1 answer
133 views

Heisenberg Uncertainty Principle (Nielsen and Chuang Box 2.4)

Giorgos Giapitzakis
  • 251
2 votes
1 answer
98 views

Fault-tolerant code and the error rate

Adam Zalcman
  • 14.8k
2 votes
2 answers
92 views

Why are orthogonal quantum states represented as collinear in the Bloch sphere?

glS♦
  • 19.6k
2 votes
1 answer
112 views

How to obtain the unitary operator to get specific partial trace?

Michael.Andy
  • 23
1 vote
2 answers
84 views

get_statevector() not working with Qiskit Aer's statevector simulator

mars34
  • 33
2 votes
4 answers
64 views

Inference on real hardware using a pre-trained quantum model on a simulator

forky40
  • 5,067
3 votes
1 answer
105 views

HHL algorithm: how running the process $N$ times gives the vector components of the solution?

Ohad
  • 1,237
2 votes
2 answers
80 views

Preparing a superposition state modulo $k$

MonteNero
  • 1,161
1 vote
1 answer
91 views

Confusion about quantum walks and the quantum walk operator

Mark S
  • 7,921
3 votes
1 answer
108 views

Show that $E_k=(I\otimes\langle e_k|)U(I\otimes|e_0\rangle)$ implies $U=\begin{bmatrix}[E_1]&\cdots\\ [E_2]&\cdots\\\vdots&\ddots\end{bmatrix}$

Sooraj S
  • 383
2 votes
1 answer
135 views

continuous time quantum walk on a cycle - transition matrix

Mark S
  • 7,921
4 votes
1 answer
80 views

Is the post-measurement state always pure after a partial measurement?

Adam Zalcman
  • 14.8k
1 vote
1 answer
57 views

Speed versus number of qubits for RSA factorization

tulapia
  • 13
0 votes
1 answer
93 views

qiskit : how to measure multiple pauli strings

Senrui Chen
  • 51
2 votes
1 answer
92 views

How can I see the circuit that was actually executed on the device in pennylane?

R.W
  • 1,997
1 vote
1 answer
111 views

Show the linearity of $(\langle a_m|\otimes I_B\otimes I_C\otimes \langle d_q|) U(I_{A}\otimes I_B\otimes |0_{C}\rangle\otimes |0_{D}\rangle)$

Sooraj S
  • 383
1 vote
2 answers
66 views

Errors while encoding (3 qubit code)

Craig Gidney
  • 24.8k
2 votes
1 answer
66 views

Are relative phase Toffoli gates universal for reversible circuits?

Craig Gidney
  • 24.8k
1 vote
1 answer
83 views

How to rewrite the quantum state to qubits?

luciano
  • 4,254
2 votes
1 answer
75 views

Is the assumption of constant per gate error probability $q$ in quantum computation proved , practical or valid?

XL _At_Here_There
  • 209
1 vote
3 answers
45 views

What is the maximum number of qubits to execute a circuit on real hardware with IBM Quantum Experience and Qiskit?

Elle
  • 435
3 votes
1 answer
57 views

How to simulate rectangular surface code with stim?

oscarhiggott
  • 41
2 votes
2 answers
69 views

Quasiprobability decomposition of the CZ-gate

bm442
  • 106
2 votes
1 answer
68 views

How to calculate the action of a channel on part of a quantum state?

glS♦
  • 19.6k
0 votes
1 answer
85 views

How to implement this oracle?

Craig Gidney
  • 24.8k
2 votes
1 answer
66 views

Hilbert space vs RKHS

Rajiv Krishnakumar
  • 1,043
2 votes
1 answer
51 views

Truncating the bond dimension of an MPS -- how good is the approximation?

Norbert Schuch
  • 5,097
5 votes
1 answer
50 views

Action of a channel on an "unphysical" state

User101
  • 548
3 votes
1 answer
61 views

How do we compute quantum walks for a graph?

Mark S
  • 7,921
2 votes
1 answer
46 views

Solving a Bloch sphere where alpha is imaginary

Richard Rodenbusch
  • 31

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