All Questions

1,532 questions
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Does an Oracle use only the eigenstates of the quantum register?

The working of a quantum oracle is still not completely clear to me and I have a few questions: As I understand it, an oracle is a unitairy quantum gate and must somehow differentiate between the ...
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How to add states on the Bloch sphere from a master equation?

Can you please help me to find an answer to this question: I am using qutip for the study of quantum systems. suppose I have calculated the solution of the master equation using the ...
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How to represent $|+\rangle$ in Python?

I am using state vectors and operator matrices to test out my knowledge in a Python program. How would I represent the state $|+\rangle$ in Python? I want to then perform several operations in a ...
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Understanding CNOT gate for indirect measurement

I am trying to write a simple circuit to understand the process of finding the set of parameters such that the cost function of that circuit in question is minimized. For that I understand one has to ...
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Understanding the “Controlled Rotations” used in the HHL algorithm

In the HHL paper they make use of what they refer to as a controlled rotation in order to invert the eigenvalues of a Hermitian matrix $A$, which is what I am trying to understand. I understand the ...
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Experiments stuck on VALIDATING ibmq_16_melbourne

Since yesterday I'm trying to run on the new composer (quantum-computing.ibm.com) both new experiments (never run before) and older experiments (that have been successfully run and completed some ago) ...
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IBM Q [Grover's Algorithm]

How to apply the changes on circuit design for Grover's Algorithm n=5 in ibm q ? i Have tried n=3 which is already present there.
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What is the motivation for Weyl matrices in quantum information theory?

Quantum Entanglement and Geometry — Andreas Gabriel (2010) — Sec: 2.3.4 ~p. 11 Another basis for $d\times d$-dimensional matrices that has proven to be quite useful in quantum information theory is ...
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Simulating a 3-local Hamiltonian Term

This may be a fairly basic question, but in Nielsen & Chuang, the following circuit is given for simulating $\exp\left(-i\Delta t Z_1 \otimes Z_2 \otimes Z_3\right)$: which uses an ancilla qubit ...
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D-Flip Flop in FPGA's as quantum computer [closed]

I believe that there is some way to make a quantum computer by programming an FPGA with the D Flip-Flop. The D Flip Flop uses a square wave as the clock signal and another wave, the data input, that ...
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Quantum fidelity simplified formula while both of the density matrices are single qubit states

I have a question while reading the quantum fidelity definition in Wikipedia Fidelity of quantum states, at the end of the Definition section of quantum fidelity formula, it says Explicit expression ...
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I'm trying to program a controlled gate as the figure below in Qiskit. Should it be sufficient to separate and control individually the Hadamard gates?
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Clarification of the “Calculations” section of the (HHL09) paper

I am reading this paper entitled "Quantum algorithm for linear systems of equations" and am trying to understand a portion of the algorithm described on page 2 and in more detail in the appendix ...