Questions tagged [programming]

For questions about writing code to be executed on a quantum computer, or to more generally simulate some aspect of it. For questions about a specific programming language, please also include a more specific tag.

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11
votes
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171 views

Does the Curry-Howard correspondence have a quantum-specific type system?

In Wikipedia we can read that the Curry–Howard correspondence is a correspondence between formal proof calculi and type systems for models of computation. In particular, it splits into two ...
7
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1answer
176 views

Gradient boosting akin to XGBoost using a quantum device

I am currently trying to implement a boosting algorithm akin to XGBoost with a quantum device. The reason is that I want to make use of a quantum device to train weak classifiers. However, as far as I ...
5
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71 views

Quantum implementation of arcsin

I am looking to implement a quantum version of the arcsinus function. Such a problem is motivated by the HHL algorithm where $x\mapsto 1/x$ and $\arcsin$ can be used to get $1/x$ from the ...
5
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311 views

How to build a quantum circuit representing the Ising Model?

Can someone explain to me how to build a quantum circuit representing the Ising Model? I just want to understand how to represent the Ising Model for the purposes of quantum state label classification....
4
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88 views

Solving higher-order (unconstrained) binary optimization problems with QAOA without quadratization

I am aware that it's possible to use QAOA to solve QUBO problems. However, I've recently seen some sources mentioning the possibility of solving HOBO/HUBO problems using QAOA as well [1][3]. While I ...
4
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0answers
50 views

Inequality constraints on D'Wave (using PyQUBO)

Inequalities cannot be directly converted into a qubo form 0⩽ Expression ⩽ N We can introduce a slack variable and convert it to an equality problem: ⟹ Expression + s = N where: s ∈ Z, s ∈ [0,N] Since ...
4
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0answers
126 views

General mixed integer linear programming problem with quantum computers

I was wondering if anyone had a sample code for running a general MILP problem. I saw some coding for some very specific problems and I thought they were kind of far away from what we needed. $$ \text{...
4
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79 views

`execute()` hangs and eats memory

Used memory-profiler to check why I get memory spikes in what I though were small circuits. The circuit itself is constructed using ...
4
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0answers
86 views

Grover search for basis states with complex coefficents and multiple marked states

I tried to run Grover's search for basis states with complex coefficients, including the marked basis (complex coefficients because the states are obtained from inverse QFT), but it could not amplify ...
3
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0answers
35 views

Trying to simulate Weak Value Amplification using QuTiP

Weak Value Amplification is a procedure in which one consider a bipartite Hamiltonian of the form $H = g A \otimes B$, where $A$ is called system, $B$ is called meter and $g$ is the extremely small ...
3
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31 views

Implementation of the “Quantum Verification of Matrix Products” algorithm

I would like to implement a Quantum Verification of Matrix Products, using Ambainis OR Burhman algorithm but I don't know how to start. There isn't much documentation about it, and no circuit in the ...
3
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1answer
87 views

Simulation of a helium molecule using Qskit

I am trying to compute the ground state energy of He-He using VQE. For this purpose I have utilized Qskit and have written the following script: ...
3
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0answers
119 views

Implemented QAOA returns wrong result

I try to apply QAOA algorithm to find minimal energy state of the Hamiltonian: $H_A = \frac{1}{2}\sigma_z^1 + \frac{1}{2}\sigma_z^1\sigma_z^2$ It is expected that with p=2 my variational should ...
3
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42 views

Run VQE for parametrized quantum circuit with ancilla qubits

Let's say we have the following circuit (picture and code shown below), and now the $q_0$ is an ancilla qubit. If the system of interest has only two qubits, Is there a way to use only $q_{1,2}$ as my ...
3
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72 views

How can I measure a qubit on a generic axis on Qiskit?

I'm trying to prove Bell's inequality by following the one made by Wigner, that is: $P(+_a,+_b) \le P(+_a,+_c) + P(+_c,+_b)$ And that this proof is NOT satisfied for angles between the various axes $\...
3
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32 views

D-WAVE QUBO Matrix Form

I am trying to write down this problem (friend/enemy graph) in a polynomial matrix form in order to understand quantum annealing better, but it seems like the problem should actually be split into ...
3
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59 views

IBMQ backends: How can I know the repetition rate and depth limits of real devices?

When trying to execute complex quantum circuits on IBMQ real devices, one can encounter a typical error (ERROR_RUNNING_JOB) with the message ...
3
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2answers
172 views

How to repeat circuit efficiently and reliably in IBM Qiskit?

I'm having a problem in IBM Qiskit with my qubit identities switching places during transpilation. I've been told by developers on the Qiskit slack server that there's currently no built-in way to fix ...
3
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0answers
57 views

What is the best way to use loop statements on a quantum computer?

I am interested in solving a time dependent linear partial differential equation of the form $Ax=b$ which, in classical computing, would amount to looping over solutions of $Ax=b$ where $b$ is updated ...
3
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1answer
103 views

VQE jobs do not appear in queue

I am trying to calculate the ground state energy of some simple molecules using 'MolecularGroundStateEnergy' tools in qiskit. When I run the calculations for very small molecules (e.g. H2, HeH+) the ...
3
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1answer
143 views

Installing Q# in jupyter

I have followed all steps described in https://docs.microsoft.com/en-us/quantum/install-guide/qjupyter But I am unable to get through part 3. It is showing syntax error in Python terminal in Jupyter ...
3
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1answer
114 views

Implementing QFT

I would like to know if there is a way to: Implement Quantum 'Functions' e.g the QFT of QFT* containing several single-qubit operations? Implement such operations on an arbitrary number of qubits and ...
3
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0answers
49 views

Does anyone have any really good quantum computing illustration packages or frameworks for visually teaching various aspects of QC?

I'm focusing on training non quantum physics / non math majors - software engineers to be specific (and the interested senior executive that wonders by) and am bewildered by the lack of adequate ...
3
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0answers
110 views

How does batching work in the optimizer loop of the VQC algorithm in Qiskit Aqua?

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 ...
3
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0answers
283 views

Grover's search for solving TSP

Consider the modified version of the Traveling Salesman Problem where you are searching for a path of length less than some $k$. We can solve this problem using Grover's search where we encode each ...
3
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175 views

What is “Lindblad Superoperator” in Stochastic Master Equation

I was reading a paper titled "Using a Recurrent Neural Network to Reconstruct Quantum Dynamics of a Superconducting Qubit from Physical Observations" and was confused about a stochastic master ...
3
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0answers
68 views

How to define initial state $\rvert \Psi(0) \rangle \equiv \rvert 1, -1 \rangle \otimes \rvert 0 \rangle_{\text{cav}} $ of a system in QuTiP?

Say, we have a $\require{mhchem}\ce{^87Rb}$ atom having an electric dipole transition on the $D_{1}$ line and we have two hyperfine ground states, one on $F = 1$ and one on $F = 2$ level. So, we take ...
3
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21 views

Synchronous Interactions Between Quantum and Macroscopic Systems

Synchronous Interactions Between Quantum and Macroscopic Systems Lester Ingber This project calculates synchronous quantum systems and macroscopic systems with well-defined interactions. I would ...
3
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0answers
55 views

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 ...
3
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0answers
84 views

Bell State 11 not working for parity curve

I am currently writing a script to automate the creation of parity curves for a 2 qubit bell state and then calculate fidelity and proving entanglement from that (inspired by this paper). It was going ...
3
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0answers
132 views

Measurement inconsistency in Qiskit

I am using Qiskit in an algorithm. In the end, I am measuring exactly a register of 4 qubits but the histograms show states with 5 qubits. This is the code I used: ...
3
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0answers
69 views

How to calculate the $r^{\text{th}}$ digit of $\sum ^{j−1}_{p=i}d^p_{\pm k}$ using PyQUBO?

I am going to implement "turn circuit encoding" method of Coarse-grained lattice protein folding on a quantum annealer(Babej, Ing & Fingerhuth; 2018) using PyQUBO to run on the DWave qbsolv ...
3
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0answers
86 views

What are reasonable noise/dephasing parameters for QuEST to emulate state-of-the-art quantum computers?

The QuEST code allows for simulation of quantum computers taking dephasing and depolarizing noise into account via one and two qubit dephasing and depolarization. What are realistic parameters for ...
3
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0answers
528 views

Qiskit Python program cannot connect to QE API

I am just getting started with Qiskit and IBM Quantum Experience, so please forgive my newby question. I have a IBM Quantum Experience account and I generated an API token. I used the generated ...
2
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0answers
57 views

is it possible to eliminate a certain possibility of an outcome of 3+ qbits

Let's say I have n qbits each in a superposition $\begin{pmatrix} \frac{1}{\sqrt{2}}\\ \frac{1}{\sqrt{2}} \end{pmatrix}$ so each possible outcome has a probability of $\frac{1}{2^n}$. Is it possible ...
2
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0answers
61 views

Why there're two axis of rotation when I'm trying to visualize this time-evolution?

This is a follow-up question of the problem I posted earlier. The following diagram illustrates my question: I'm trying to perform the time evolution of a random Hamiltonian. The green vector ...
2
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0answers
26 views

What would be a real-life example of using a quantum workflow oriented tool/environment, such as through Orquestra?

Recently, a unified quantum software and hardware platform, Orquestra was released. My question is, what could be a real-life (step by step) example of using this kind of workflow? As existing quantum ...
2
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0answers
62 views

Two qubit gate decomposition in using Qiskit

I am writing some python code to be able to optimise the total error in two qubit gate decomposition. I am using the Qiskit module qiskit.quantum_info.synthesis.two_qubit_decompose My question relates ...
2
votes
1answer
42 views

Design NISQ Circuit with StrawberryFields

I am trying to design this circuits with strawberry fields. However I could not connect my first and second qubit mode: orange boxes are beam splitters, blue boxes are phase shifters. The green box ...
2
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0answers
43 views

QISKit not installing in PyCharm

I am attempting to setup a PyCharm project to study and work through the QISKit textbook. However I seem to be running into a propblem seting it up. I have setup a python enviroment via anaconda (...
2
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0answers
49 views

Calculating exact expectation values on ibmq_qasm_simulator

In order to calculate the exact expectation value of a Pauli operator in some state using local qasm_simulator, I do ...
2
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0answers
49 views

Qiskit CircuitStateFn.eval() on more than 16 qubits

The definition of Qiskit CircuitStateFn.eval() is as follows: ...
2
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1answer
71 views

API error when trying to access IBM Quantum Computer using IBMQ API Token

I'm trying to write a code so that if the token exists then it loads the account or else it asks the user for the API token. Below is the code for reference: ...
2
votes
1answer
51 views

Get the gates after fusion optimization in Qiskit statevector simulator

I tried to obtain the gates after fusion in Qiskit-aer statevector simulator. What I can find now is that it provides a backend option saying fusion_verbose (bool): Output gates generated in fusion ...
2
votes
1answer
50 views

How to improve accuracy of ground energy values from a VQE

Using the Qiskit textbook I have been using a VQE to find the ground state energy of Hydrogen at different interatomic distances on a quantum machine. However, the average energy value I will always ...
2
votes
1answer
103 views

Expectation value of operator - python

I am suposed to solve following problem: Calculate the probability $P_n(x > X)$ that a particle in then n-th eigenstate is found at a position with an x-value larger than X. Here it is convenient ...
2
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1answer
277 views

Qiskit issues with Apple Silicon?

Edit/summary: Everything below this first paragraph is my original question posted several days ago and involves a lot of speculating on a problem I knew less about at the time. The purpose of this ...
2
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0answers
55 views

Getting Choi-matrix of a subsystem

In Qiskit, for a given QuantumCircuit object, you can compute its Choi-matrix via the corresponding Choi object, for example: <...
2
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0answers
37 views

How to implement the Maximum or Minimum Searching Algorithm (QUMMSA) circuit in Quirk?

I am Java and Python programmer who started self-learning Quantum Computing a couple of months back. The journey has been thus far very tough. I have been using QisKit and Quirk to learn by in ...