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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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8
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1answer
145 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 ...
4
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1answer
54 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 ...
3
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1answer
19 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. ...
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0answers
51 views

Cirq: Any interesting introductory level example using 2D grid of qubits?

I have already asked this question on reddit.com/r/QuantumComputing. Cirq supports to create quantum circuits composed by qubits having 2D grid structure. We have been preparing educational ...
2
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2answers
112 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 + \...
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3answers
153 views

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

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.
0
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1answer
17 views

Is there a function that returns the probability of measuring a particular state in Cirq?

It is possible to use cirq.simulate and then the final_state keyword to get the final wavefunction of the circuit, however, the ...
0
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1answer
37 views

How to do a $C-PH$ gate in google cirq

I know that I can just use the $RZ$ gate to replace the $PH$ phase gate. But I need a way to implement the controlled phase gate $C-PH$ this cannot just be replaced with a $CRZ$ gate.
2
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0answers
29 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 ...
3
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0answers
98 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. ...
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2answers
51 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 ...
4
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1answer
115 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 ...
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0answers
50 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, ...
3
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1answer
104 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 ...
1
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1answer
88 views

How do you start a simulation with a random initial state in Cirq?

How do you create a random initial state by modifying the $2^{n}$ vector amplitudes instead of starting every simulation at $|0000...000\rangle$?
3
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1answer
215 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 ...
2
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2answers
92 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 $RZ(\pi q/2)$.
3
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1answer
248 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 ...
3
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1answer
115 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 ...
4
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1answer
47 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/...
5
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1answer
85 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 ...
3
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1answer
73 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? ...
1
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1answer
67 views

Why are these circuits not producing the same output?

I am simulating the phase shift algorithm on the Quirk platform. Even when the endian-ness of the built-in inverse QFT gate is corrected for, the circuits still output different results. Shouldn't the ...
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1answer
55 views

Why are these circuits not producing the expected output?

This circuit was created on the Quirk platform. I'm trying to implement a basic case of phase estimation. For some reason, I'm getting this strange result. When the Inverse QFT is broken down, it ...
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1answer
43 views

Do these outputs seem normal for the order finding algorithm?

I'm sorry for posting so many questions about this specific problem, but I just want to make sure that I am implementing an algorithm correctly. I am simulating the order finding algorithm (finding ...
2
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1answer
100 views

Is this the correct quantum circuit for the order-finding algorithm?

The algorithm is being implemented on Cirq, with the goal of finding the smallest $r$ for cooprime numbers $x$ and $N$ satisfying the equation $x^r \ = \ 1($mod $N)$. I have set $x \ = \ 2$ and $N \ = ...
6
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1answer
218 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 $...
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0answers
84 views

Would this quantum algorithm implementation work?

I am trying to implement the order finding algorithm on Cirq finding the minimal positive $r$ for coprime $x$ and $N$ satisfying the equation $x^r \ = \ 1$(mod$ \ N$). In my case, I have set $x \ = \ ...
2
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1answer
60 views
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2answers
143 views

Is it possible to create controlled gates with an exponent in Cirq?

Is it possible to create controlled gates with an exponent in Cirq? For example, a controlled $\sqrt Z$ gate.
3
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2answers
273 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.
5
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1answer
381 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 ...
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3answers
2k views

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, ...