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,
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Is Qiskit more popular than cirq? Why?
It seems like most people are using Qiskit, what's the difference?
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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.
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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 ...
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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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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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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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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?
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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 ...
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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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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?
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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 ...
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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 ...
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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/...
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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 ...
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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 ...
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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.
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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 $RZ(\pi q/2)$.
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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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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 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
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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 ...
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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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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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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?
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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 ...
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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 ...
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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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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 ...
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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 ...
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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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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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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
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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, ...
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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-...
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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:
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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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how to flatten a cirq.Circuit with CircuitOperation
I have a cirq.Circuit that uses a CircuitOperation, something like:
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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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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 ...
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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 ...
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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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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, ...
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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 ...
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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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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 ...
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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 ...
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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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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
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What does PhISwap gate mean in Cirq?
I am currently using the Cirq pakage and when drawing the circuit structure, I constantly encountered the PhISwap gate, like in here. What does this gate mean?
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