All Questions

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 ...

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 ...

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

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

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

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 ...

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 ...

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 ...

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 ...

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 ...

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?...

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 ...

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 ...

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 ...

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,...

I have read the following paper by Dumitrescu et al. To make a Unitary Coupled Cluster (UCC) ansatz, one prepares with the following equation. $$ | \psi_{\rm{UCC}} \rangle = U(\theta)|\mathrm{HF}\...

If I act a CNOT gate on quantum circuit: from qiskit import QuantumCircuit qc = QuantumCircuit(2, 2) qc.cx(0, 1) it means that qubit_0 is the control qubit, and ...

Self reducibility is when search version of the problems in a language reduce to decision versions of the same problems. NP-complete problems are self reducible. Are QCMA complete problems self ...

I can't seem to find anything, but this seems like something that should be possible.

Over the years I encountered different explanations of quantum computing advantage over classical computers. But I am not sure which explanations are in fact valid and which are not. Quantum ...

Consider the function $f:\{0, 1\}^3\to\{0, 1\}^2$ with $f(x, y, z) = (x \oplus y, y \oplus z)$. How would you construct its standard unitary representation?

I have a computer science background, and I'm interested in studying 'quantum algorithms' and anything that is related like 'quantum complexity'. I would like to have all important resources that is ...

I've playing around with a binary classification problem with a dataset of size 1000 examples and 5 features. I'm using the VQC algorithm from the Qiskit package the that uses a feature map and a ...

I have been trying to implement a ripple carry adder using qsikit in IBM Q Experience. I was able to implement full carry adder but I am having trouble with ripple carry adder. I am able to add 100 + ...

After reading about quantum computers, for a high school research paper, a few questions arose concerning quantum logic gates. At first, it seems that quantum logic gates are in essence various ...

I have the following problem: I want to create a q# operation for generating a random integer from 1 to max and return the generated number. What algorithm do I need? What does the q# code look like? ...

I am very new to quantum computing and I have recently started to experiment with qiskit module in python, by following tutorials and implementing simple algorithms....

I am a beginner at QC, currently going through a paper on Quantum Anonymous Voting. Please clarify the orthogonal property described in the following scenario. Consider $n$ voters $V_{0}, V_{1}, V_{2}...

When I type this: IBMQ.load_account(), I am getting this error. What does this mean, and how can I rectify it? ...

I am struggling with the density matrix for diagonally polarized photons. Can I think of diagonally polarized photons as a mixture of vertically and horizontally polarized photons?

I came across a "new" type of quantum computer - photonic quantum computing. Is this type of technology of interest here? You may read about an example here. I wonder how many types of quantum ...

Just like other classical and quantum key distribution protocols, BB84 is vulnerable to "man"-in-the-middle attacks, where Eve pretends to be Bob to Alice, and Eve pretends to be Alice to Bob. The ...

I would like to do a quantum tomography on two q-bit state. Recently, I successfully did so for one q-bit based on Nielsen-Chuang. They advise to use this formula for one q-bit density operator ...

Consider the modified version of the Traveling Salesman Problem where you are searching for a path of length lass than some $k$. We can solve this problem using Grover's search where we encode each ...

How do I measure the first qubit of an entangled vector, say \begin{pmatrix} 1 \\ -1 \\ 0 \\ 0 \\ \end{pmatrix} is what I get on the end of Deutsch's algorithm. If I get it right, I should now ...

I am a beginner at QC. I was going through the basics of multi-qubits I encountered a state $|2\rangle|3\rangle$. I want clarification on the following points: Can I write $|2\rangle$ as $|10\...

Please, be patient with my question I already read that there is a heuristic that makes superposition a fact of reality. In addition, this superposition, when observed, it has a state of 0 or 1. ...

Could you please give a direction/reference towards realising the following using any set of realisable quantum gates $$\boxed{|S_{n}\rangle = \frac{1} {\sqrt{n!}} \sum_{S\in P_n^{n}} ( \,-1) \,^{\...

Suppose Alice needs to transmit a bit of information about something which happened just before $t = 0$ to Bob who is light years away from Alice. Entangled pairs of qubits, $\left|00\right> + \...

Has anyone used or considered color-space and color superposition for Qutrit work? A classical color-sphere has black and white at its poles, a grey scale as its axis, pure spectral colors as a color-...

Where does QEC fit in the larger picture of the execution of a fault tolerant quantum algorithm? For QEC, there is an initial preparation of the qubit state and the ancillary qubits; then a "noisy ...

I'm picturing the control equipment on the inside of an ISS wall with the part that needs being cold being on the outer side. I imagine this has been considered and if so, was the idea rejected for ...

I don't understand this "trapped ion (qubit implemented by the internal state of trapped ions)" One qubit implemented by the internal state of trapped ions (plural)? "Consider an ion trap. The ions ...

When I access IBM Q backend with qiskit code, an error occurs. from qiskit import IBMQ qt = 'xxxxxxxxx' IBMQ.save_account(qt) IBMQ.load_accounts() The error ...

I saw a video in which a guy from IBM was explaining (very generally) quantum computing, it's difference with classical computing etc. The talk was not technical at all, it was intended for a broad ...

What are the infrastructures needed to build a cloud quantum computing service like IBM Q Experience? It seems this is not a trivial task. IQX has been running for more than 3 years and yet it is ...

There are many different physical implementations of qubits: NMR, spin qubit, N color center in diamond, superconducting qubit, trapped ions, photonics quantum computing, topological qubit, etc. ...

We know that solving a hidden subgroup problem over a non-commutative group is a long standing problem in quantum computing even for groups like $D_{2n}$ (alternatively can be written as $\mathbb{Z}_n ...

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 ...

Just need some clarification: Results derived as the output of "running" a "quantum circuit" constructed from "quantum gates" are distributed in a certain way, based on the design, and the multiple ...