All Questions

Consider a bipartite state $\rho$, and let $\Pi^A\equiv \{\Pi^A_a\}_a$ and $\Pi^A\equiv\{\Pi^B_b\}_b$ be local projective measurements. Suppose that measuring $\rho$ in these bases gives uncorrelated ...

In the period finding algorithm (see the picture), through the standard procedure in quantum computing algorithms, we have $$U_f|\Psi\rangle|0^n\rangle=\frac{1}{\sqrt{2^n}}\left(\sum_{x=0}^{2^n-1}|x\...

qubitOp, offset = qp.to_ising() print('Offset:', offset) print('Ising Hamiltonian:') print(str(qubitOp))

If we have the following matrix: $$\frac{1}{\sqrt{2}}\begin{pmatrix}1&1&0&0\\ 1&-1&0&0\\ 0&0&1&-1\\ 0&0&1&1\end{pmatrix}$$ How do we find the output for ...

I am trying to verify the accuracy of the Quantum Phase Estimation as outlined in the Qiskit textbook lab 3 (https://qiskit.org/textbook/ch-labs/Lab03_AccuracyQPE.html). Please I wanted to know if ...

I have a 32 qubit grover's algoritm however whenever I run it on the simulator that IBM offers it always ouputs a probability of 1 on every single result. Is there a way to run circuits larger then 32 ...

How can I make intervals for free parameters when I use VQE function? (https://qiskit.org/documentation/stubs/qiskit.algorithms.VQE.html) I have built a parametrized ($\theta_1,...,\theta_n$) circuit ...

I have some trouble to understand the proof in Nielsen&Chuang about Knill-Laflamme conditions. The conditions: Let $C$ be a quantum code and $P$ the projector onto $C$. Suppose $\mathcal{E}$ is a ...

Is it possible to translate the above circuit into an equivalent one where the number of interaction gates with the first qubit is 1?

Let us consider a noise channel $\mathcal{E}(\rho)=\sum_i E_i \rho E_i^{\dagger}$, where $\{E_i\}$ are one choice of Kraus operators associated to it. I assume I will perform error correction and that ...

Can you describe how to convert some QUBO problem $$f(x_1, ..., x_n) = \sum\limits_{1 \le i < j \le n} \alpha_{i,j} \, x_i \, x_j$$ into its equivalent quantum circuits? Is it preferrable to start ...

I have encountered different matrix of operator "the Square Root of NOT gate". For example, the matrix is specified here: $\sqrt {NOT} = \frac{1}{2}\left( {\begin{array}{*{20}{c}} {1 + i}&...

I want to freeze core orbitals of my molecule and I know ElectronicStructureProblem has the possibility (es_problem = ElectronicStructureProblem(driver=driver, q_molecule_transformers=...

I have noticed that some CNOT gates (for instance, between qubits 1 and 2 in ibmq_casablanca) display an error rate of 1 while typical error rates are of course ...

I am currently studying a model of a quantum (atomic) clock. And in this paper, I came across the term "Free evolution for a period T": Free evolution for a period T where a phase ...

The quantum volume is typically taken as a popular metric to determine the capability of a quantum computer to solve complex problems. Since the end goal is to develop quantum computers that can solve ...

qiskit.chemistry.FermionicOperator here is very useful for converting fermionic operators to qubits operators. qiskit.chemistry ...

Given $\ \hat{W}=\mathbf{1}_{A B}+\sigma_{x}^{A} \otimes \sigma_{x}^{B}-\sigma_{y}^{A} \otimes \sigma_{y}^{B}-\sigma_{z}^{A} \otimes \sigma_{z}^{B} $ how can i show that for every separable state $\...

How do you build a circuit for a modified Toffoli gate using only local unitary operations and CNOT operations? The two-qubit unitary operation is given by: $\text{diag}\{1, 1, 1, e^{i\phi}\}$.

The IBM Qiskit Portfolio Optimization sample finally provides an array similar to [1,0,1,1] representing the 4 digits as the stocks. So does the ...

This is an important result in Quantum Computing because it means that the Hamiltonian of a Quantum System can be encoded as a sequence of real numbers and their corresponding Pauli Operator. How do ...

This is the first time I am using the IBM quantum computer. I tried to run a circuit (see below the first picture) but the results I got don't match the theoretical results shown (see below the second ...

I've used the function result.time_taken to know the amount of time used to execute a task on the real chip, but I don't understand if the result is in seconds or ...

There are various options for error correction. For example, the Shore code or a whole class of surface codes. But I don't really understand at what level they should be implemented. For example, I ...

Im trying to put the QFT circuit in my qiskit circuit but im having trouble: ...

I'm trying to answer the following question about the BB84 protocol from Nielsen and Chuang's Introduction to Quantum Information. As I understand it, the string $b$ is determining whether we are ...

Based on my limited and poor understanding, a quantum circuit in the "one clean qubit" model of quantum computation generally acts on a single pure (clean) qubit tensored with $n-1$ qubits ...

This is a question desguised as a rant. There is a similar question here, What's the point of Grover's algorithm if we have to search the list of elements to build the oracle?, but the answers have ...

If I have a circuit with 3 qubits and repeated gates as follow: ...

We can say that $X (\cos \frac{\theta}{2} |0\rangle + e^{i \phi}\sin \frac{\theta}{2} |1\rangle) = \cos \frac{\pi-\theta}{2} |0\rangle + e^{-i \phi}\sin \frac{\pi-\theta}{2} |1\rangle$, a fact that ...

Consider a simple two-qubit gate such as the CNOT. The typical presentation of this gate is $$\text{CNOT} = |0\rangle\!\langle0|\otimes I + |1\rangle\!\langle1|\otimes X,$$ with $X$ the Pauli $X$ gate....

I am in a study group learning about quantum computing using O'Reilly - Programming Quantum Computing. I'm a developer, not a physicist. :) I feel like my question is rudimentary but I can't seem to ...

here's the code I'm using to generate 3 quantum circuits with the same structure (They're only differed by the first U3 gate on the qubit): ...

I have a Pauli channel with disjoint probabilities $P_I$, $P_X$, $P_Y$, $P_Z$ (meaning $P_I + P_X + P_Y + P_Z = 1$) corresponding to Pauli errors I, X, Y, Z. Is there some way apply this Pauli ...

It is suggested in various sources that a possible approach to representing classical data as a quantum state is simply to take the binary sequence $x$ and turn it to $|x\rangle$ (i.e., "basis ...

Say you have something like a general-coefficient $n$-qubit W-state, i.e., $$ |\psi\rangle\equiv\sum_{j=1}^n a_j X_{j}|0\rangle^{\otimes n} \ , $$ where $a_j$ are normalized complex coefficients. ...

If we have this given circuit: So the output for $|0\rangle$ will be: $\frac{1}{\sqrt{2}}\left(|00\rangle + |11\rangle\right)$ And we have this given circuit: What will be the output for $|00\rangle$...

In Qiskit I can construct a computational basis statevector in the following fashion ...

Background: I am given to understand that the steps of Quantum State Tomography (QST) are as follows for a single qubit: The qubit is in the state $\psi=a_0|0\rangle+a_1|1\rangle$ with density matrix ...

Hi Is there anyone here who has experience using Existing Quantum kernel trick to do Feature importance like RFECV/PCA/ Random foreset which can give importance score for each feature.

It is known that an "upside-down" CNOT is equivalent to a "normal CNOT" surrounded by Hadamard gates as shown in this picture. I am wondering whether there is a similar circuit ...

I am trying to code finance portfolio optimisation problem into a quantum annealer, using the Hamiltonian Ising model. I am using the dwave module ...

I agree that this may not be an easy question to answer. But lately, I increasingly come across the fact that many news materials and research papers in the field of quantum technologies say that at ...

Can you help me to configure the FakeOpenPulse2Q() to produce more realistic pulses? The code below instantiates 2 circuits and generates the waveforms for each. ...

The Quantum Cramer-Rao Bound states that the precision we can achieve is bounded below by: $$(\Delta \theta)^2\ge\frac{1}{mF_Q[\varrho,H]},$$ where $m$ is the number of independent repetitions, and $...

If so, why? How to create the RYY-gate in the composer?

How can I construct a CNOT gate using a CZ and H gates? And I also need to prove it using these identities: \begin{equation} H = (1/\sqrt{2})(X+Z)\\ XZ = -ZX\\ X^2 = Z^2 = H^2 = 1\\ HXH = Z\\ HZH = X\\...

How can we draw a circuit that is based on the gates $H, CZ$ that implements $CNOT$. I know that the $H$ gate is like that: And also the $CZ$ gate is: But I'm not sure how to draw this with the ...

I am using Qiskit's opflow and its CircuitSampler to evaluate matrix elements / expectation values. Now, going beyond ...

Given a quantum circuit consisting of two qubits, how is the compiled unitary of the circuit computed when we have different input type gates? (X-gate, H-gate are single-input gates, CNOT is a 2-input ...