# All Questions

2,181 questions
Filter by
Sorted by
Tagged with
4 views

### Minimum number of ancilla qubits required to make a transformation unitary?

Background The counterpart of a NOT gate is the CNOT gate. They make use of ancilla qubits to achieve this. Question Given an arbitrary non-unitary transformation what are the minimum number of ...
22 views

### IBM Q experience - error code 520

I have been running a variational circuit optimizing the parameters on the "melbourne" device. The system launches multiple jobs in parallel, and only gets the jobs accepted that my credit allows. The ...
16 views

### Find the Q-Experiment tutorial for beginner

Where I can find the previous Quantum-Experiment tutorial for beginners? (the one that was under https://quantumexperience.ng.bluemix.net/qstage/#/account)
19 views

### What does the error rate on the IBMQ website mean？

How is the error rate pointed by the arrow defined? How did you get it? thanks!
30 views

### Quantum random number generator

Can we generate quantum random numbers through Qiskit? I want to try the random number generator without using optics or noise.
15 views

### OpenPulse: Where to get current pulse definitions for standard gates?

Is backend.defaults().cmd_def and backend.defaults().pulse_library kept updated regularly? Is this the correct place to pull the best calibrated pulses for the standard gates? I am working on a ...
36 views

### How is a quantum computer programmed?

After lightly reading into quantum algorithms and the hardware of quantum computers, I subsequently started wondering how a quantum computer is programmed so it executes the desired quantum algorithm ...
50 views

### Getting a layout for qubits in Qiskit

I'm trying to use Qiskit's built in transpiler passes to do the following. I would like to take a quantum circuit and allocate the logical qubits to physical qubits. The tutorial doesn't really ...
18 views

### How many iterations does Grover’s search need to find one out of $M$ marked items?

How many iterations are needed in Grover’s quantum search for finding one out of M marked items in a database containing N items (for 1 < M < N/2)? I would have thought we just reduce the size ...
10 views

### How's quantum noise and fault-tolerance related to symplectic geometry and geometric quantization?

Gil Kalai often speaks of the apparent connection between symplectic geometry, geometric quantization, and quantum noise. He is known to describe one of his focus areas as: (...) properties and ...
47 views

### What can be done so far with cloud quantum computing?

As a developer myself, I still do not understand what can be done so far with services like AWS BRAKET or IBM CLOUD QUANTUM COMPUTING. Can someone explain me the practical purpose of it in the present?...
45 views

### How to obtain the tensor-product of two quantum operations (superoperators) explicitly?

I have an amplitude damping channel, denoted as a superoperator $\mathcal{E}$ with operator elements \begin{matrix} E_1=\begin{pmatrix} 1 & 0 \\ 0 & \sqrt{1-r} \end{pmatrix},\quad ...
39 views

### Can quantum entanglement be expressed in terms of knot theory?

While writing this answer I was wondering whether the analogy of the nature of entanglement in the GHZ state with Borromean rings is more than a mere analogy (cf. Aaronson's lecture). The question ...
49 views

### Understanding the monogamy of entanglement with respect to GHZ States

Given the GHZ state wrt n = 3: $\frac{|000⟩ + |111⟩}{\sqrt{2}}$, I'm trying to understand how the principle of monogamy of entanglement manifests here. I came across this explanation. Let’s say ...
40 views

### Bloch sphere and quantum operations [closed]

Evidently the Bloch Sphere is used as a graphical representation for any single qubit system, although what does it mean at an intuitive level? Moreover, the manipulation of qubits still seems unclear,...
46 views

80 views

### Prove that the state $\sum_{S\in P_n}(-)^{\tau(S)}|S\rangle$ is invariant up to a phase when changing the basis
I am trying to prove that the $|S_{n}\rangle$ is $n$-lateral rotationally invariant, where $|S_{n}\rangle$ is defined as |S_{n}\rangle=\sum_{S \in P_{n}^{n}} (-)^{\tau(S)}|S\rangle\equiv\sum_{S \in ...