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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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What are physically allowed CNOTs for Rigetti's 19 qubit chip and Google's 72 qubit BristleCone chip?

For each IBM quantum chip, one can write a dictionary mapping each control qubit j to a list of its physically allowed targets, assuming j is the control of a CNOT. For example, ...
rrtucci's user avatar
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10 votes
2 answers
5k views

Is Qiskit more popular than cirq? Why?

It seems like most people are using Qiskit, what's the difference?
nighthawk30's user avatar
9 votes
1 answer
2k views

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.
Victory Omole's user avatar
8 votes
1 answer
451 views

Is there a mistake in the VQE Ansatz in Cirq's tutorial?

I have been going through Cirq's VQE background tutorial and after examining the Ansatz it seems to me that the only layer that actually affects the final measurement is the rot_x_layer. The other ...
dncolomer's user avatar
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7 votes
3 answers
407 views

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: ...
Calum Macdonald's user avatar
6 votes
2 answers
1k views

How to prepare a specific initial state of three qubits?

I would like to prepare the following initial state for variational quantum algorithms: $$ \sin\theta_1 \sin\theta_2 \sin\theta_3 |000\rangle + \sin\theta_1 \sin\theta_2 \cos\theta_3 |001\rangle + \...
Ashy's user avatar
  • 375
6 votes
1 answer
1k views

Why is this implementation of the order finding algorithm not working?

I asked a question about this earlier, but I am still coming across problems in my algorithm implementation. I am trying to implement the order finding algorithm on Cirq finding the minimal positive $...
Jack Ceroni's user avatar
5 votes
3 answers
5k views

Overview of Cirq, qiskit, q#, ibmq(circuit board), other [closed]

What is the difference between these frameworks or languages? What are the pros and cons of each of these? Do you know any similar framework/platform/language that gives some more advantages?
Rishwi binnu's user avatar
5 votes
2 answers
793 views

N-Toffoli on Cirq

I am looking for guidance in more generally how to developed n-bit gates in Cirq. I am working on a QNN paper and I need to develop a n-controlled gate to be able to measure the cost function of the ...
Enrique Segura's user avatar
5 votes
1 answer
555 views

List of qubit locations with cirq

As far I understand, qubits in cirq are labelled by their positions on chip. For example print( cirq.google.Foxtail.qubits ) yields ...
James Wootton's user avatar
5 votes
1 answer
581 views

Bloch sphere visualization using Cirq, ProjectQ, PyQuil

Is there a way to visualize the Bloch sphere using Cirq, ProjectQ, and/or PyQuil, as it is possible using plot_bloch_vector in Qiskit?
Marija Scekic's user avatar
5 votes
1 answer
237 views

Where does the Xmon simulator from Googles cirq framework its entropy from?

Measurements create entropy as we all know. But computers themselves are deterministic machines. Most devices use processor heat as a source for random number generation as far as I know - which has ...
sycramore's user avatar
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5 votes
1 answer
551 views

Moments-based quantum circuit in Cirq

In Cirq, quantum circuit consists of moments, which in turn consists of operations. This is different from Qiskit/OpenQASM, which doesn’t have the concept of moments. What is the design philosophy ...
Junye Huang's user avatar
5 votes
1 answer
370 views

Using parametrised values and 'Symbols' in Cirq

I'm just wondering how one should go about using parametrised values and the Symbol object that gets resolved at runtime? For example, if I would like to implement the gate $R_x(\theta) = e^{-i\theta/...
QC90's user avatar
  • 51
4 votes
1 answer
1k views

Creating an ansatz for variational quantum algorithms?

I was recently reading through the tutorial on the Cirq documentation about creating variational quantum algorithms, and I came to the section on ansatz preparation. The way that the ansatz is ...
Jack Ceroni's user avatar
4 votes
1 answer
2k views

How to set a starting state in cirq?

I'm learning how to use the cirq library. Every time I set up a circuit the starting state of the qubits is $|0000..0\rangle$. Is there any way to make the starting state different? I'm thinking of ...
Apo's user avatar
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4 votes
3 answers
1k views

How do I create my own unitary matrices that I can apply to a circuit in Cirq?

I am trying to simulate Deutsch's algorithm, and I need to apply the oracle function matrix to my circuit.
Jack Ceroni's user avatar
4 votes
2 answers
513 views

How is $X^q$ equal to $RX(\pi q)$?

I've seen in google cirq that a $X^q$ gate is converted in openqasm to $RX(\pi q)$, why is that? Same for $S^q$ into $RZ(\pi q/2)$.
Reda Drissi's user avatar
4 votes
1 answer
271 views

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 ...
ryanhill1's user avatar
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4 votes
1 answer
1k views

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 ...
Lorenzo B.'s user avatar
4 votes
1 answer
468 views

How to add noise to existing gates in Cirq?

I would like to add noise to existing gates in Cirq, i.e. to define something like NewGate = cirq.Gate(qubit) followed by ...
user52305's user avatar
4 votes
1 answer
95 views

Estimate run time of Cirq circuit on forthcoming Google quantum computer

Calling cirq.Simulator().run(..) on your circuit to get an idea of how it'd behave if you were to run on Google's (apparently) forthcoming real hardware is fine and dandy. Is there a way to estimate ...
P.Windridge's user avatar
4 votes
1 answer
367 views

How to implement NM Algorithm for Variational Quantum Eigensolver?

First of all: thanks for reading again. I appreciate the feedback I have gotten from this community the past weeks as I started to feel ready to ask questions about quantum computing topics. I am ...
Enrique Segura's user avatar
4 votes
1 answer
60 views

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 ...
GuestUser's user avatar
4 votes
1 answer
250 views

cirq.ControlledGate from sub-circuit generator

In Cirq, is it possible to take a sub-circuit generator and use it as the sub_gate in a cirq.ControlledGate? ...
curiousStudent's user avatar
4 votes
0 answers
138 views

Variational Quantum Eigensolver (VQE) by scipy minimize in cirq does not work

I tried to make a cirq program calculating an eigenvalue of the observable by VQE. Inspired by the qulacs VQE tutorial, I defined a cost function from the expectation value of the observable with ...
Weongyu Lee's user avatar
3 votes
1 answer
412 views

is cirq suitable for simulation of quantum error correction?

I experimented with stim and qiskit for QECC simulations. They both have limitations : for example stim has no support for non-clifford operations (qiskit does); qiskit has no support for multiple ...
unknown's user avatar
  • 2,217
3 votes
2 answers
204 views

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-...
ryanhill1's user avatar
  • 2,503
3 votes
2 answers
916 views

GridQubit in Cirq vs LineQubit

It's perhaps a very silly question, but in what ways is it advantageous to use GridQubit vs LineQubits to develop quantum circuits? Specially to develop ansatz ? Are GridQubits Cirq's way of ...
Enrique Segura's user avatar
3 votes
1 answer
2k views

How to add control to gates in Cirq?

My question is very simple. I know there is a method to add a control to previously defined gates. I saw in the API of cirq that there is a command Controlled gate (here). I'm not understanding though ...
Apo's user avatar
  • 545
3 votes
1 answer
538 views

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 ...
Amin's user avatar
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3 votes
1 answer
369 views

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: ...
elizalexander's user avatar
3 votes
1 answer
85 views

Cirq seems to output 0 instead of |2> with qutrits

I am experimenting a bit with qutrits on Cirq and came across a problem: my output is 0 when it should be |2>. I defined my qutrit as follows: ...
Q.Ask's user avatar
  • 195
3 votes
1 answer
178 views

Cirq : Reference for Toffoli decomposition

I was trying to find a reference for the 7 T-gate decomposition of the Toffoli gate given by Cirq. The decomposition originates from the the one used for CCZPowGate as given in the doc string here ...
Madhav Vijayan's user avatar
3 votes
1 answer
485 views

How to use Cirq to transpile circuit to custom native gate set?

I am trying to use Cirq to compile arbitrary quantum circuits to custom native gate sets, e.g., to use the Cirq compiler to generate quantum circuits for different quantum computers (IBM, Rigetti, ...
nils's user avatar
  • 33
3 votes
1 answer
247 views

Cirq error models

I have two questions about error channels used in Cirq to model noise quantum circuits. The first one is that for the deplorizing error model, one common setting is to set larger error rates for two-...
ironmanaudi's user avatar
3 votes
1 answer
259 views

Multiplying quantum circuits in cirq using * and computing "expectation values"

I am reading cirq guide about Simulation and there is an example in "Expectation values" paragraph that I don't understand. Everything boils down to the following snippet: ...
Fallen Apart's user avatar
3 votes
1 answer
530 views

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 ...
quest's user avatar
  • 626
3 votes
2 answers
55 views

How to compose a larger circuit onto a smaller circuit in Qiskit, adding extra quantum registers to some fixed list

$\newcommand{\ket}[1]{|{#1}\rangle}$ I have a Qiskit quantum circuit for multiplication $M$, that I want to compose onto another qiskit quantum circuit for inner ...
Aditya Morolia's user avatar
3 votes
1 answer
113 views

how to flatten a cirq.Circuit with CircuitOperation

I have a cirq.Circuit that uses a CircuitOperation, something like: ...
sailx's user avatar
  • 355
3 votes
1 answer
171 views

cirq.Ry complains that it needs one argument

When I try to put an Ry gate into my circuit in cirq, I get an error saying that it only takes one argument. ...
Craig Gidney's user avatar
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3 votes
1 answer
276 views

How to Properly Cite Amazon Braket?

This is a fairly basic question, but how does one cite Braket in BibTeX style? A similar question was asked for Cirq in How to cite cirq in a scientific article? but I am unable to find a similar page ...
Ken Robbins's user avatar
3 votes
1 answer
324 views

How to convert Pennylane decompose_hamiltonian to Cirq PauliString?

I have a matrix that I would like to decompose into a Pauli String. Pennylane's qml.utils.decompose_hamiltonian does this and returns a list of coefficients and a list of operations representing the ...
Ruby's user avatar
  • 31
3 votes
0 answers
184 views

Quantum Optimization via Quantum Label Classification in Quantum Circuits

I have been reading Farhi and Neven's paper on quantum neural networks on quantum circuits. I also found an example - albeit not ideal as pointed out by a couple of users - thank you - in here. ...
Enrique Segura's user avatar
3 votes
0 answers
223 views

Measuring the expected energy of a quantum circuit

I implemented the following circuit: I am interested in measuring the expected energy of the circuit. I am using Cirq. I am wondering what are the next steps. Sorry if the question seems very basic, ...
Enrique Segura's user avatar
2 votes
3 answers
315 views

Controlled NOT gate which flips target when at least one of the control qubits is |1>

I would like to have a controlled NOT gate which flips my target qubit when at least one of the control qubits is |1>. I would like to be able to do this for arbitrary n. For a system with 2 ...
Q.Ask's user avatar
  • 195
2 votes
2 answers
1k views

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!
user3886914's user avatar
2 votes
1 answer
104 views

Wrong expected value from cirq PauliString

I have to compute the exact expectation value from a state vector obtained after running a circuit. While I was running my code, I found different weird outcome so I decided to create few tests and I ...
Michele Cattelan's user avatar
2 votes
1 answer
417 views

Encoding Numeric data as a quantum circuit in TFQ

I am working on a dataset where I have 6 input features that are numbers in the range of 1 - 1000 that need to be encoded as a quantum circuit. I am using TensorFlow Quantum for my research. While I ...
Lakshit Dabas's user avatar
2 votes
1 answer
615 views

Cirq - Print state of qubit

Seeing a state of qubit is too complicated in Cirq I don't want to simulate, I would be happy for debugging, to see the probability/ amplitude of the state of a qubit, without measure and simulate ...
Ron Cohen's user avatar
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