Questions tagged [cirq]

A python framework for creating, editing, and invoking Noisy Intermediate Scale Quantum (NISQ) circuits. It is a Python library for writing, manipulating, and optimizing quantum circuits and running them against quantum computers and simulators.

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How to use pass_operation_over with cirq.Operation? [closed]

Lately I saw a pull request in the Cirq GiHub repo where some dev said a test should be defined, with these constraints: You need to find a case where a ...
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Setting the Initial State of Density Matrix Simulation in Cirq

I am trying to use the DensityMatrixSimulator in Cirq. I want to append gates to the circuit conditional on measurements. In order to reduce computational resources, I am trying to run these ...
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How to create an observable: 'Identity \tensor Pauli gate' in Cirq

I am working on an implementation of the RQAOA algorithm on the Maxcut problem in Cirq. My graph G has n vertices. And after running a QAOA circuit with n qubits I obtain a state gammabeta (a vertical ...
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In Cirq, how do you display circuit diagrams that are "prettier" than the ones displayed by default?

This is a duplicate of a question that was asked on the Cirq issues page. I'm duplicating this question to increase it's visibility. The standard way to print circuits in Cirq is by calling ...
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Best way to compute $\langle a|B|a \rangle$ in Cirq, where a is a state obtained running circuit A. And B is a different Quantum Circuit

I am implementing RQAOA in Cirq. After running regular QAOA to find an optimal state a (This I have done successfully). I need to calculate $\langle a|Z_iZ_j|a\...
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Why wont my custom controlled gates in Cirq work on a simulator?

To initialize a state in Cirq, I created a custom controlled rotation and a custom rotation gate. The effect of applying the custom controlled gates to the qubits doesn't seem to affect the state. ...
2 votes
1 answer
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Is there a way to present conjugate transpose of a Y Pauli rotation as a Cirq Operator?

Given: Ry(theta) acting on one qubit I'm trying to use existing Cirq Operators to build the conjugate transpose of the above gate. I need the operator to produce the exact unitary of the given gate ...
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What are the libararies for Machine Learning on NISQ Chip? And What are the roadmaps?

Nowadays quantum learning is hiring. And we can see mainly two different area. One of them is variational algorithms part. And the other one is classical learning for quantum systems like NISQ. (Some ...
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What is a good program to practice using a quantum algorithm? Should I use Cirq or Qiskit?

I am starting to learn about Quantum Computers and Quantum Algorithms. I also started reading about Qiskit and Cirq. I really like learning about them and hopefully I can be a Software Engineer with ...
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Cirq: n-qubit GHZ state

I am trying to write $n$ party GHZ state but at the end of the day, it seems like bi partite state. I am missing a detail. Here is my code ...
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Cirq: Result of rotating qubit measurements never come [0 1] or [1 0 ], always come as [0,0] or [1,1]

I am creating a 2 qubit entangled state: ...
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How to convert a dataset of different values in [0,1000] to quantum data for training a model using Tensorflow QuantumHaving?

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In Simon's algorithm, is there a general method to define an oracle given a certain periodicity?

I have to implement Simon's algorithm in Cirq. I have problems determining the oracle $f(x)$ defined such that $f(x)=f(x\oplus a)$ from a certain value of $a$. Given a random $a$, is there a general ...
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How do you represent one-qubit rotations in two registers as a $4\times 4$ unitary matrix?

Let's say you have a circuit that performs a Z-rotation in the first register, and a Y-rotation in second register. How can we express this "moment" in terms of a 4x4 matrix, i.e. a two-...
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1 answer
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Access and set_state during quantum computation simulation in cirq

The documentation for Cirq mentions the possibility to step through a circuit's moments, and access the exact wavefunction via step.state_vector(), and edit set it ...
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Does Cirq support GPU acceleration?

I'm wondering if Cirq does (or plans to) support GPU acceleration of matrix operations, including density matrix simulations. I would like to speed up training and evaluations of variational circuits ...
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Does TensorFlow Quantum tfq.convert_to_tensor work on custom gates?

I'm trying to use Cirq with TensorFlow Quantum to simulate a variational quantum classifier. There's a tutorial on the TFQ website on building a quantum neural network to classify a simplified version ...
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1 vote
2 answers
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Why is the Measurement Result Always 1? (expected to find uniformly random measurement)

I created a $|0\rangle$ state then applied $H$ gate to get $\frac{1}{\sqrt{2}}(|0\rangle+|1\rangle)$ and then I meausred my state. But I always found 1. I expected to find 0 and 1 uniformly random ...
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Cirq.simulate expectation value of a Hamiltonian

I want to simulate the final state of an ansatz in cirq using simulate. Now I want to calculate the expectation value of a Hamiltonian. How do I do this? I can only find simulator.run examples in cirq....
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How to learn parameters in a quantum circuit, given an interference pattern?

Using cirq, I have the following quantum circuit, with three parameters: phi, alpha and beta: ...
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Cirq - Measure Density Matrix Function Getting First Element

Hello I am using measure density matrix function like that: ...
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Implementing the HHL algorithm with negative eigenvalues (Cirq)

How do I implement the HHL with negative eigenvalues? This paper (https://arxiv.org/abs/1803.01486) says that: what if $\lambda<0$? This problem actually does not hard to solve, since we can ...
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Cirq-Measuring a State with Rotation Matrix

I have this state: $$p |\text{GHZ}\rangle \langle \text{GHZ}| + (1-p)\rho$$ And after creating this state I have this code lines: ...
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Bit Flip, Separable state and Several Question about Cirq

1)I want to use noise model for my state and bit_flip is not defined on cirq. ...
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Multiple Bipartite Entangled State in Cirq

I am trying to create this state: rho = = q . rho_{1,2} + r . rho_{2,3} + s . rho{1,3} + (1-q-r-s) . rho_separable And I wrote this code: ...
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Cirq: Creating an arbitrary gate for an arbitrary number of qubits

How do I create an arbitrary unitary gate for an arbitrary number of qubits in Cirq? Note: A solution for creating a single qubit gate is answered by Thomas W from this post. How do I create my own ...
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Producing $|ghz\rangle\langle ghz|$ State in Cirq

I could manage to produce 3 qubit ghz state in Cirq. But I don't know how I can produce $|GHZ\rangle\langle GHZ|$ in Cirq Here is my code for 3 qubit ghz state Can you help me please for improving my ...
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Can I run Cirq on IBMQ?

Google's quantum computer is not yet available for the public. Is it possible to run Cirq on IBM's quantum computers, instead of Qiskit? And if so, how can I do it? Thank you!
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Output a Cirq gate as a Numpy array?

How do I output a Cirq gate as a Numpy array? For example, I would like to print a Pauli X gate cirq.X as ...
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Wrong Expectation value when implementing a VQE for the Heisenberg Hamiltonian

I tried to implement an extended Heisenberg-Hamiltonian as an extra exercise further than my homework. My Hamiltonian is the following: $H = \sum_{NN} \sigma_x\sigma_x + \sigma_z\sigma_z$ I try to ...
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XX and YY and ZZ Hamiltonians in vqe

I'm trying to implement a vqe in cirq and I have sort of a brain knot. I have a 4 qubit chain with periodic boundary condition. So in fact a 2x2 qubit grid. Now 2 of them each are coupled. How do I ...
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Implementing Cirq Coding Gates

Can someone please help me making these gates on CIRQ programming: Decrement Gate (-1) Splitter Gate (If possible) I was having trouble implementing these and was not sure if it's possible either. ...
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Running Google Cirq example code from their webpage -- where do I find information about PROCESSOR_ID?

I'm just ttrying to run the simple example code in Google's Cirq startup page: https://cirq.readthedocs.io/en/stable/google/engine.html I think I have the access authorized correctly via Google's ...
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Reordering commuting gates in cirq to reduce circuit depth?

The main functionality for ordering gates in a cirq circuit that I'm aware of is using the predefined insert strategies of cirq.Circuit.insert(). As far as I see, ...
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Create this state using CIRQ Coding language [closed]

I needed help with CIRQ coding as I'm quite new to Quantum Computing. I read the tutorials on CIRQ but don't really understand it. I'd be very thankful if someone could help. A program to create the ...
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What is the analysis of the Bell Inequality protocol in Cirq's 'examples'?

This question is taken from https://github.com/quantumlib/Cirq/issues/3032. The "standard" protocol measures Alice's and Bob's qubits in different bases, while the one in Cirq measures in ...
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Applying a gate to all line qubits without explicitly listing them in Cirq

Say we have a custom gate CG, defined by a unitary matrix U, and line qubits qubits in Cirq. ...
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Visualizing custom gates in Cirq

I'm trying to visualize a custom gate in Cirq. I have through this page, which briefly mentions how to create custom gates in Cirq. However, I'm getting errors when trying to visualize it. My current ...
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How to build a controlled two-qubit gate?

I have a two-qubit gate with below unitary: ...
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Can not build circuit unitary for a three-qubit gate in Cirq

I am trying to implement a three-qubit gate in an eight-qubit circuit. The method I use is the same by which I create my two-qubit gates with no issues. I produce the unitary of the gate and then ...
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Adding Quantum State Tomography Step to HHL Algorithm (Cirq)

Over the past month, I have been learning about the HHL algorithm and am interested in extending the Cirq implementation to include the quantum state tomography step to extract the amplitudes or ...
1 vote
1 answer
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How to assign values to the symbols in a parametrized Cirq circuit without running it?

Is there a way to use a ParamResolver or Sweep to assign values to the symbols in a parameterized Cirq circuit without running it? For example, something like: ...
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1 answer
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Can't append multiple times with self-defined oracle

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How to cite cirq in a scientific article?

What would be the best/prefered bibtex entry for citing cirq ? Is this ok ? ...
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Can We Currently Import Quantum Datasets (Datasets Containing Quantum Data) Onto NISQ-era Quantum Computers?

I'm still investigating the TFQ whitepaper. In one section of the paper, the authors say this with respect to Quantum Datasets In general, [a quantum dataset] might come from a given black-box ...
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Implementing U2-Gates on Cirq

I am interested in using the QASM2Cirq methods to make this gate: u2(0, np.pi, q[0]). How can I build that object using Cirq rather than QASM string value passed onto cirq.
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VQE for Beginners : Using Tutorial and Cirq

I have been following this tutorial: https://dkopczyk.quantee.co.uk/vqe/ I am using Cirq to try to teach myself VQE, replicate their results, and also try to understand more about ansatz for ...
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Placement of quantum circuits

I have a question concerning the placement of quantum circuits on Google devices. Consider the following code: ...
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A bug during CIRQ installation

I had the following problem with an installation of the Cirq. When I typed python -m pip install cirq, I got the following line: "Cannot uninstall 'sympy'. It is ...
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Cirq: easiest way to compute qubit Hamiltonian expectation value with number of shots

I was wondering what was the easiest way to take a qubit Hamiltonian, and get an expectation value estimated with a certain number of shots over a parameterized quantum circuit (or ansatz) with Cirq.
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