Quantum Computing Stack Exchange
Quantum Computing Stack Exchange

Most Popular

more tags
1500 questions
10
votes
4 answers

How is quantum teleportation generalized to qudits?

In an answer to a previous question, Generalization for n quantum teleportations, Craig Gidney states: The more complicated way to generalize teleportation is figuring out how to make it work on qutrits and qudits instead of only qubits. Basically,…
user820789
  • 3,302
  • 12
  • 42
10
votes
1 answer

Quantum attack on hash functions

The line of questioning is inspired by the pick one trick in Section 4 of the PDF version of the paper Quantum Attacks on Classical Proof Systems - The Hardness of Quantum Rewinding (Ambainis et al., 2014). Slides available here. I don't fully…
user1936752
  • 2,859
  • 1
  • 8
  • 20
10
votes
3 answers

Do any educational quantum computing toys or devices exist?

Question inspired by this article from IEEE Spectrum on blocks containing different polarization filters for use in classrooms, and my previous question on representing the three-polarizing-filter experiment in quantum computing terms. Here I want…
ahelwer
  • 4,128
  • 1
  • 13
  • 33
10
votes
3 answers

Is there a simple rule for the inverse of a Clifford circuit's stabilizer table?

In Improved Simulation of Stabilizer Circuits by Aaronson and Gottesman, it is explained how to compute a table describing which Pauli tensor products the X and Z observable of each qubit get mapped to as a Clifford circuit acts upon them. Here as…
Craig Gidney
  • 36,389
  • 1
  • 29
  • 95
10
votes
2 answers

What can tensor networks mean for quantum computing?

I am trying to understand what the importance of tensor networks is (or will/could be) for quantum computing. Does it make sense to study tensor networks deeply and develop them further to help pave the way towards quantum supremacy? If so, how…
dumkar
  • 209
  • 1
  • 5
10
votes
2 answers

Classical Memory enough to store states up to 40 qubits quantum system?

As a part of a discussion with my 'classical' friend, he insisted that making a a state machine for calculating the outcome of quantum computer is possible; so, simply calculate the outcomes of (known) algorithms on supercomputers and store their…
mando
  • 355
  • 3
  • 11
10
votes
2 answers

Is there a Hamiltonian simulation technique implemented somewhere?

I was wondering if there was some code available for Hamiltonian simulation for sparse matrix. And also if they exist, they correspond to a divide and conquer approach or a Quantum walk approach?
cnada
  • 4,754
  • 1
  • 8
  • 21
10
votes
1 answer

Minimum number of CNOTs for a 4-qubit increment on a planar grid

Recently I've been wondering how high NISQ machines will be able to "count". What I mean by that is, given the most optimized increment circuit you can make, how many times can you physically apply that circuit to qubits in a secret initial state…
Craig Gidney
  • 36,389
  • 1
  • 29
  • 95
10
votes
2 answers

How can I calculate the inner product of two quantum registers of different sizes?

I found an algorithm that can compute the distance of two quantum states. It is based on a subroutine known as swap test (a fidelity estimator or inner product of two state, btw I don't understand what fidelity mean). My question is about inner…
Aman
  • 483
  • 3
  • 12
10
votes
3 answers

What is the simplest algorithm to demonstrate intuitively quantum speed-up?

What's the simplest algorithm (like Deutsch's algorithm and Grover's Algorithm) for intuitively demonstrating quantum speed-up? And can this algorithm be explained intuitively? Ideally this would be also illustrate clear how quantum interference is…
Steven Sagona
  • 1,119
  • 7
  • 16
10
votes
2 answers

CNOT Gate on Entangled Qubits

I was trying to generate Greenberger-Horne-Zeilinger (GHZ) state for $N$ states using quantum computing, starting with $|000...000\rangle$ (N times) The proposed solution is to first apply Hadamard Transformation on the first qubit, and then start…
Satvik Golechha
  • 123
  • 1
  • 8
10
votes
3 answers

Why can all quantum circuits be converted into circuits that use only real matrices?

I know that you need to add an additional ancilla qubit to "keep track" of whether or not you are in real space or imaginary space, but how exactly does this work? What is the proof for this? I tried looking online but I could not find a proof. I…
Rydberg
  • 309
  • 2
  • 6
10
votes
1 answer

How does the number of copies affect the diamond distance?

Suppose we are given two maps $\Phi$ and $\Psi$ such that $$\|\Phi-\Psi\|_{\diamond}\leqslant\varepsilon.$$ What can we say about $\left\|\Phi^{\otimes t}-\Psi^{\otimes t}\right\|_{\diamond}$? Is it upper-bounded by $t\varepsilon$? Is the result…
Tristan Nemoz
  • 6,137
  • 2
  • 9
  • 32
10
votes
1 answer

Any simple description of a circuit for Yamakawa-Zhandry algorithm?

Recently, popular sources (including Aaranson's blog and Quanta Magazine) have made it look like the recent Yamakawa-Zhandry algorithm is akin to Shor's algorithm, in the sense that it could demonstrate quantum advantage soon if done with sufficient…
Mauricio
  • 2,296
  • 3
  • 25
10
votes
1 answer

Categories and types of quantum inspired algorithms

I have a question concerning "quantum-inspired" algorithms. There seem to be several types of algorithms that fall into this category. Some examples are: Ewin's dequantized algorithms Tensor Networks A couple of optimization examples by…
sheesymcdeezy
  • 1,746
  • 6
  • 25
1 2 3
…
99 100