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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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Density matrix positive semi definite? [closed]

Why doing quantum tomography in cirq, I ended up getting a density matrix which is not positive semi-definite. Why is this so?
1 vote
1 answer
43 views

How does the cirq compilation process work?

Cirq compilation process. I cannot find the documentation that describes the internal structure of the library Cirq by Google. There is much information related to high level functions, but none ...
-1 votes
2 answers
39 views

How to do quantum tomography on a subsystem of 2 of 30 qubits in cirq?

I have a 30 qubit system and I need to do quantum tomography on a subsystem of 2 of its qubit. How can I do this in Cirq?
1 vote
0 answers
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Finding partial trace in CIRQ

Suppose I have a 30 qbit system, due to computational complexity, I can't find the density matrix of the system. But is it possible to find the partial trace of the a sub-system of 2 qubits out of 30 ...
3 votes
2 answers
48 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 ...
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1 answer
61 views

How to implement a depolarizing noise channel for qutrits using cirq?

Anyone have any idea how I can implement a depolarizing noise channel for qutrits using cirq? Say using the kraus operators within a class inheriting from cirq.Gate or so?
2 votes
1 answer
180 views

Merge two Y**0.5 gate into a single Y gate

How can I merge two consecutive cirq.Y**0.5 gates into a single cirq.Y gate with a transformer? I can use ...
1 vote
2 answers
78 views

How can we see on Cirq that Google Sycamore has 54 qubits?

Hello, can you explain how to see in Google Cirq that the figure above is a 54 qubits quantum computer ? thanks
1 vote
0 answers
23 views

How to convert a custom observable matrix to a Cirq observable for simulation?

I aim to conduct a Cirq simulation using a custom observable. However, the measure_observables function in Cirq requires an Iterable of cirq.PauliString, making it challenging to directly use a custom ...
1 vote
1 answer
390 views

Marking a specific quantum state in the oracle function in the Grover's algorithm

I have a simple implementation of Grover's algorithm. As depicted in the results below, the oracle function marks the state |111>. How can I change the Oracle function to mark |010>? ...
1 vote
1 answer
59 views

cirq entanglement qubits

The following code originates from a third-party, although, I have added the commented line containing "UNCOMMENT THE START OF THIS LINE". ...
1 vote
2 answers
291 views

How to create a multicontrol mcx gate or operation in cirq

In qiskit the method to apply a multi control with more than 2 control qubits is: qc.mct ( listcontrols,targetbit,listancillas, mode=mode[i]) What is the ...
0 votes
1 answer
200 views

How to change the qubits of a cirq Circuit?

I am constructing generic circuits, and I would like to change the qubits after creating the circuits. Is there a way in cirq to do so? for instance: ...
1 vote
1 answer
122 views

Measuring a specific observable using cirq

I am simulating a circuit in cirq, and I need to measure an observable $$A(\theta) = R^\dagger_z(\theta)XR_z(\theta),$$ and I am not quite sure how to do that. My first thought was to apply these ...
2 votes
2 answers
583 views

VQE Cirq example

Is my understanding correct that in this example the Hamiltonian measurement is not performed through measuring individual Pauli operators because all its terms are mutually commuting? So, for each ...
1 vote
1 answer
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Need help regarding building a custom VQE

I want to write code for a custom Variational Quantum Eigensolver (VQE) capable of computing eigenvalue(s) for non-Hermitian systems, based on this paper. I have formulated a cost function (provided ...
2 votes
1 answer
149 views

In Cirq, how do I separate transpilation from execution in simulator.simulate()?

In Qiskit, there are explicit transpile (where a circuit is transpiled to primitive gates) and backend.run (where the circuit is executed in either statevector simulation or real hardware) steps. What ...
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113 views

Initialize circuit by density matrix (i.e. mixed state) by Cirq, Qiskit, QuTip

I want to do a simulation involving: mid-circuit measurement (i.e. based on the measurement result of some qubits to append further gates on other qubits; e.g., Pauli error correction in entanglement ...
1 vote
0 answers
50 views

Tensorflow_quantum hybrid models tf-quantum

I am trying to QCNN for MNIST classification equivalent to that built in. I’m having problems trying to pass my quantum circuit built with cirq as a Keras layer. Here’s what I have: ...
4 votes
0 answers
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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 ...
1 vote
0 answers
67 views

How to create a 3-D state (array) of qubits in qiskit or cirq etc?

I want a 3-D cube-like array for state of qubits, on which I want further to implement different sets of rotations, etc, for cryptographic means. You can create a 2D grid qubit in cirq with ...
1 vote
1 answer
190 views

If Statement OpenQasm 2.0

in the documentation for OpenQasm 2.0 it says one can use an if statement like so: if(c_reg==int) Quantum Operation. However, I would like to execute the following: ...
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49 views

How to best implement this algorithm?

I am trying to design an algorithm to find a solution to a certain problem. I have N qubits which encode the problem (let's call them the problem qubits) and one check_qubit (which is flipped to |1>...
2 votes
3 answers
309 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 ...
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.
1 vote
1 answer
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Classical control of an entire sub-circuit in cirq

I would like to evolve a quantum state through an entire sub-circuit in my circuit based on classical control. I am aware of the current state of classical control in cirq (https://quantumai.google/...
1 vote
0 answers
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Is there a way to find the computational resources required to perform a simulation of n- qubits in Cirq similar to qsim?

I’m trying to model basic spin chains in 1D using VQE (ideal circuit) with cirq and qsim. The models have between 10-20 sites and varying interactions (nearest neighbour, next to nearest neighbour etc)...
1 vote
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How to Find a circuit that evolves from one density matrix to another(qiskit or cirq)

given two density matrices, dmBefore and dmAfter, I want to generate(find) a circuit in Qiskit or Cirq that starting initaliazed with dmBefore ends with dmAfter after it's execution. Is it possible?. ...
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: ...
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1 answer
162 views

AttributeError: module 'cirq_google' has no attribute 'Foxtail'

I have installed cirq in my anaconda environment by using the command: pip install cirq When I ran the code below to print the ...
1 vote
1 answer
192 views

Resolving AWS-Braket - ValidationException: An error occurred (ValidationException) when calling the CreateQuantumTask operation

I have a quantum circuit for the Markovian Reservoir Engineering[MRE] Model, written in cirq (frontend) and trying to run it on Ionq hardware, using qbraid credits. This is all being done on qbraid ...
0 votes
0 answers
184 views

tensorflow, tensorflow-quantum, tensorflow-federated latest version compatibility?

I have been working with on some research on tensorflow, tensorflow-quantum and tensorflow-federated and the problem with that is I just can't install those three at my google colab and I tried ...
1 vote
1 answer
315 views

How we can perform measurements on an X, Y or Z basis in cirq?

How we can perform measurements on an X, Y or Z basis in cirq? Is there any function where we can give the list of qubits and measurement basis as an argument and get the output?
2 votes
1 answer
160 views

Generalizing a brick-wall circuit acting on qubits to acting on qudits

Recently, I have been creating a "brick layer" circuit of random unitary gates (each acting on 2 qubits) which acts on a n qubit register using cirq. A typical circuit looks like this. (...
1 vote
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Two-time correlators in Cirq?

Is there a way to calculate two-time correlators in Cirq directly? For example, suppose we have an initial mixed state described by a density matrix $\rho_0$, and we want to obtain in our quantum ...
1 vote
1 answer
94 views

Efficient simulation of circuit with variable depth using Cirq

I have a program that needs to evaluate several Cirq circuits by using both simulators the Simulator() and ...
2 votes
0 answers
37 views

How to take gradient of the `tfq.layers.State` output?

I am using the following code for building a quantum circuit as a custom tf.keras.layers.Layer: ...
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0 answers
76 views

Topmost Universal Gate Based Quantum Simulator?

I am Elijah I'm interested in Drug Discovery and Materials Simulation. I want to purchase a gate based Quantum Simulator for research. I received a proposal. Full State Simulator 30 Qubits on Laptop, ...
3 votes
1 answer
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how to flatten a cirq.Circuit with CircuitOperation

I have a cirq.Circuit that uses a CircuitOperation, something like: ...
1 vote
0 answers
89 views

How can i describe Custome Gate Sets in Cirq?

i try to create a Custome GateSet with the CompilationTargetGateset class but it does not work. ...
3 votes
1 answer
519 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 ...
1 vote
1 answer
262 views

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 ...
1 vote
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Is there a method in pyQuil to create logical boolean gates

is there another way to represent a boolean gate. The straight forward way would be to define a gate my a matrix and then apply this gate to the circuit. What i mean by that? For Example an AND-Gate ...
1 vote
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Convert an integer to its basis state in Cirq

I am trying to implement Quantum Adder using QFT in Cirq. I previously did the same problem using Pennylane, in which I converted an integer into its Basis state using the BasisStatePreparation method ...
1 vote
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147 views

How to rewrite this Cirq problem into Qiskit?

I have a following example problem in Cirq, representing a very simple operator given by $$ \hat{H} = a^\dagger_0a_2 + a_0a^\dagger_1 + 0.9\, a^\dagger_0a_1a^\dagger_2a^\dagger_3 + a^\...
2 votes
1 answer
118 views

Use parametrized quantum circuit output amplitudes for training in tensorflow

I am trying to train a quantum neural network in tensorflow_quantum (tfq). Using cirq.Circuit I have set up my circuit. I now need to wrap it in a keras model for ...
1 vote
1 answer
84 views

Two Qudit custom gate error in Cirq

I am trying to build two qudit CX (d-dim) gate. and getting below error. There is no issue in the unitary matrix. Please suggest to resolve the error.
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1 answer
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Interpretation of Qudit measurement output in cirq

Here [+1] represents X gate for qutrit. How the Counter value is coming to 5? which is the measurement outcome(q0q1q2->102). Even for (q0q1q2->101) also counter value is 5. In total, for this 3 ...
0 votes
1 answer
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Printing Stabilizer State of a circuit using Cirq

How to print the stabilizers for a given circuit using Cirq (just like in Qiskit)? For example, if I have the following cluster state and make a circuit using Cirq. I give the circuit as input, and I ...
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Why importing cirq_ionq gives an unexpected argument error

I'm trying to install cirq_ionq, a python library for running cirq circuits on IonQ's quantum hardware. However, when I try importing it I get an unexpected argument error: ...