Questions tagged [q#]

Q# is a domain-specific programming language used to express quantum algorithms. This tag should be used for questions related to creating/programming quantum algorithms using the 'Q#' language. If the question is not related to, or arising from some quantum aspect of Q#, it might be better to ask on StackOverflow. If appropriate, also use the [programming] tag.

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Ground state energy estimation - VQE vs. Ising vs. Trotter–Suzuki

Disclaimer: I am a software engineer who is curious about quantum computing. Although I understand some basic concepts, theory and math behind it, I am by no means experienced in this domain. I am ...
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3answers
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Cirq, qiskit, q#, ibmq(circuit board), other

Which platform is the best for programming quantum computers? Which one is your personal favourite? If other mention which one it is and if possible few resources for it.
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How do these alternative Q# algorithms produce the same set of Bell states?

In the "Superposition" Microsoft quantum katas (https://github.com/microsoft/QuantumKatas/blob/master/Superposition/ReferenceImplementation.qs) the solution for Task 7 looks like this: ...
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How to add scalar to quantum string

I need a way to add scalar values to a quantum string. Say if $| v \rangle = |1 1 0 \rangle + |1 0 1 \rangle$ then $|v \rangle + 5 = |1 0 1 1 \rangle + |1 1 0 0\rangle$ Is there a known method to ...
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1answer
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How to make a time rotation in Qsharp like in Quirk spinning gates?

Qsharp have Rx Ry and Rz gates for rotation, but I need to apply a gate that leaves the Qbuit rotating continuosly like in Quirk spinning gates. https://algassert.com/quirk#circuit=%7B%22cols%22%3A%5B%...
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1answer
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Q#: dynamically assigning (or updating) multidimensional Qubit arrays

Question: how to dynamically assign qubits to variables? e.g., say I want to represent a matrix of qubits: $matrix := \{\vec{v_1}, \vec{v_2}, ..., \vec{v_r}\}$ where each vector consists of $dim$ ...
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2answers
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Q#: How to setup a project correctly (on Linux, command line)?

When setting up projects with Q# I used to start with the given Quick-Starting Guide. Following the tutorial I am able to setup the example problem and the program works well. However, there seems to ...
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2answers
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Is it possible to change the oracle in Grover's search to ponderate probabilities in multiple values search?

If I want to to search 2 values with Grover's algorithm, it outputs the same probability for both that is bigger that the no searched states that have the same lower percent. If I use an oracle ...
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1answer
31 views

Hamming with prefix oracle

I'm doing the Q# quantum katas and I'm stuck on an oracle in the Deutsch-Josza algorithm katas. Let $|x\rangle=|x_0x_1\dots x_{n-1}\rangle$ be a qubit array and $r$ be bit string of $k\leq n$. The $...
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177 views

How to construct the “Inversion About the Mean” operator?

It seems like it should be simple, based on how Nielsen and Chuang talk about it, but I cannot seem to correctly implement the Inversion About the Mean operator ($2|\psi\rangle \langle\psi| - \mathcal{...
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1answer
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How does ControlledOnInt in Qsharp make it's Grovers Oracle?

I have an example with 6 qubits for names and 6 for telephones. I encoded their relation like this: ...
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Converting a Qubits state to a binary value in Q#

In Q#, How do I store a Qubits state in a binary-based disk / hard drive for use by regular digital programs? Is this even possible?
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473 views

How to compute the inverse of an operation in Q#?

I want to implement amplitude amplification using Q#. I have the operation $A$ that prepares my initial state and I need to compute $ A^{-1} $ to implement the algorithm. Is there an easy way to do ...
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178 views

Quantum counting in Q#

I cannot seem to get an estimate for the number of solutions using the quantum counting algorithm described in Nielsen and Chuang, i.e. phase estimation with the Grover iteration acting as $U$. I try ...
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1answer
104 views

Counting in Q#: number of solutions

I have this program derived from Microsoft Quantum Katas for counting (see here): ...
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1answer
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How to see the QASM code corresponding to compiled Q# function?

I'm learning Q#. Is there any way to see the QASM code of a Q# function I write, the same way I can see the disassembly of a C# function?
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1answer
118 views

Q# factorization Method Program

Is there a method to calculate prime factorization in Q# of Visual Studio of Microsoft Quantum Development Kit? In the Python language, it is the sympy.factorint ...
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1answer
64 views

How do I multiply an integer and a double in Q#?

If I write this: function f(n: Int) : Double { return 1.5*n; } I get an error: ...
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1answer
322 views

How to measure in an arbitrary basis in Q#?

Q# has a measurement operator defined as follows according to the docs: operation Measure (bases : Pauli[], qubits : Qubit[]) : Result Where you give a Pauli gate ...
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1answer
59 views

Programmatic access to wavefunction in Q# for tests

I'm trying to write unit tests for some small Q# operations. It would be ideal if I could access the wavefunction. Is there a way to get it? I found ...
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1answer
58 views

Type error creating R gate in Q#?

The R operation in Q# is listed by Microsoft in the documentation as follows operation R (pauli : Pauli, theta : Double, qubit : Qubit) : Unit However, when I try ...
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1answer
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How do I do printf debugging in Q# in a convenient way?

When initially writing an operator in Q#, I often want to see intermediate values of registers during the computation. This allows me to check that I haven't made ...
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2answers
138 views

Can we perform quantum mechanical simulations using a quantum computer?

I'm a computer science major who's really keen on physics and quantum mechanics. I have started learning about Q# and D-Wave, but I just wanted to know if it's possible to test quantum mechanical ...
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1answer
251 views

Creating controlled R1 gates in Q#?

I know how to create controlled versions of gates like X, Y, Z. For example, a controlled X gate would be implemented by writing (Controlled X)([control],target); ...
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2answers
202 views

From Q# measurements to Bloch sphere

I would like to represent the state of a qubit on a Bloch sphere from the measurements made with Q#. According the documentation, it is possible to measure a qubit in the different Pauli bases (...
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2answers
202 views

Finding the maximum number of Q# simulatable qubits

I'm new to Q# and I was curious on how one would find the number of Q# simulatable qubits for a specific machine. I know Microsoft has an approximation of 16GB ~ 30 qubits but I wanted a better ...
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3answers
373 views

How do you send an array of qubits to an operation in Q#?

I have the following operation in my .qs files: operation myOp(qubits: Qubit[]) : () { // uses elements from the qubit array } How do I send an ...
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1answer
628 views

Practical example of Grover's algorithm (in Q#)

Is there any real example for Grover's algorithm but with real database (generated from SQL or file)? I download the Q# development kit & its example, there was one call DatabaseSearchExample ...
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1answer
100 views

Q# How to use a namespace in another project?

I have some utility operations that I'd like to use across projects. How can I import its namespace using Q# in Visual Studio 2017 in other projects?
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2answers
99 views

Is programming in quantum computer same as programming in quantum simulator in classical computer?

I just started programming in Q# and I wonder if the coding for Q# in classical computer would be the same as coding in a quantum computer. Obviously, these 2 kinds of computers work differently, so I ...
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1answer
428 views

How many logical qubits are needed to run Shor's algorithm efficiently on large integers ($n > 2^{1024}$)?

First, I know there are differences in logical qubits and physical qubits. It takes more physical qubits for each logical qubit due to quantum error. Wikipedia states that it takes quantum gates of ...
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1answer
78 views

How do I get a list of control qubits from Q# operations when tracing the simulation in C#?

I want to write code that prints out the controls of each operation executed during a simulation in Q#. For example this code prints the control counts: ...
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2answers
102 views

Does Q# have a bigint type?

Shor's algorithm works with very large integers; larger than 64 bits. So the built-in 64-bit Int type is insufficient for doing the classical processing (e.g. ...
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1answer
73 views

How do I name the adjoint of an operation in Q#?

For example, if I've defined the operation PlusEqual, I'd like to say operation MinusEqual = Adjoint PlusEqual; but this ...
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1answer
149 views

How do I write functions that modify operations in Q#?

In Q#'s type documentation, it is mentioned that you can create signatures like this: ...
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89 views

How do I produce circuit diagrams from a Q# program?

If I implement an adder operation in Q#, I'd like to see a quantum circuit diagram of what that adder is doing in order to check that it looks right. Is there a built-in way to do this?
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1answer
108 views

An algorithm with the Hadamard operator

My goal in writing this algorithm in Q# was that func would either output (1,2) or (10,20), ...
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1answer
143 views

How to add two integers in Q#?

I have programmed in C++, but I am interested in writing quantum programs. I have some experience with Microsoft's Q#, and I know about the canonical Shor's and Grover's algorithms. Can anyone tell ...
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2answers
107 views

How does one obtain amplitude information in Q#?

Is it possible to obtain amplitude information (in lexicographic ordering) for a particular qubit register in Q#? For example, in the following code: ...
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2answers
247 views

Checking value of variable using quantum approach

A beginner question after watching few videos. Say, var=a; var can be either of two values, ...