Questions tagged [noise]
For questions about different types of noise a quantum computer (or qubits) may experience; how this affects the outcome of the computation; how to reduce a specific type of noise on a specific implementation of quantum computer; or how to simulate noise.
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Clarification on Definitions of Relaxation Probabilities
In the paper Modelling and Simulating the Noisy Behaviour of Near-term Quantum Computers, when the authors discuss relaxation times ($T_1$), they define two probabilities, $P_{T_1}$ and $p_{\text{...
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Can Noise in measurements lead to non-zero probability of a state that was not originally in the state vector?
Consider the following state vector
$$\frac12 (|000\rangle + |011\rangle + |101\rangle + |110\rangle)$$
Can noise in measurements lead to a non-zero possibility of measuring the state $|111\rangle$ ...
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Improve accuracy of fake backends while remaining realistic
If I run the code
backend = FakeLima()
nm = NoiseModel.from_backend(backend)
print(nm.__dict__.keys())
I get the following output:
...
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50
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How is Pauli twirling so powerful?
So the Pauli twirling approximation gives us a quantum channel $\Phi$ that transforms a density matrix $\rho$ to:
$\Phi(\rho)\mapsto\sum_{i=0}^3 \sigma^i \rho \sigma^i,$
where $\sigma^0 = \mathbb{I}, \...
- 179
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Qiskit noisy FakeManila simulator + ZNE
I am trying to run a simple VQE calculation on H2 using FakeManila noise model and ZNE for error mitigation; see code below. The problem is that I can never reach not even close the ground electronic ...
2
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1
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49
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What are efficient methods for measuring gate noise?
In this question I'm concerned with getting detailed spectral information about analog noise in quantum gates.
Assume we have imperfect control over transitions between $\vert 0\rangle$ and $\vert 1\...
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Is there a way to implement a noisy CNOT gate using CUGate in Qiskit
Wondering if there's a way to implement the noisy version of CNOT (or CX) gate via CUGate using qiskit library for a given fidelity p?
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Overlooked noise sources in circuit-level noise
In the research of quantum error correction, noise is often classified into code capacity noise, phenomenological noise, and circuit-level noise. Among these, circuit-level noise is considered the ...
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What is the clear definition of coherent versus incoherent errors?
The noise types in quantum computing are pivotal topics frequently discussed in academic papers.
Could you provide a clear definition of coherent versus incoherent errors? Additionally, I'm keen to ...
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Most efficient way to calculate an expectation value of a noisy model in Qiskit
I want to classically simulate quantum circuits with noise. This noise can be a custom one (noise.NoiseModel()) or a fake quantum computer (...
- 373
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Qudits in NISQ Devices: Benefits Beyond Dimensional Advantages?
It's clear from foundational research that qudits can provide an enhanced control of the Hilbert space over qubits, and I've encountered references that highlight improved robustness and noise ...
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How can one obtain all calibration data which is needed to plot error_map of the ibm backend from few month ago?
I want to plot the error map of an IBM Quantum backend from the calibration data I saved a month ago. The saved file just contain qubit properties and to plot error map I would need all information ...
- 27
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2
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How can visualise the old error map of Ibm backend if one save the calibration data of the backend at that time?
I have the calibration data of an Ibm backend and now I want to plot the error map of the device at that specific time.
How can I do this?
- 27
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Qiskit Aer Noise Module
I am trying to use the following single qubit depolarizing channel (on a GHZ state for example) but the simulation histogram counts are not affected
...
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RB with Clifford: can I define my own random model?
I'd like to know how much freedom I have when setting up an RB Clifford model.
Is any Clifford circuit sample ok for benchmarking (as long as it characterizes the Clifford group)?
What are the ...
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71
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How to run Color code on STIM?
I am trying to simulate color code on STIM. I have provided my code below. But I am getting the following error
...
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How to manipulate thermal relaxation noise in Qiskit model?
I am trying to experiment with various values of T1 and T2 parameters in thermal relaxation noise.
...
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Impact of various kinds of noise on calculation of operator's expectation value
I am trying to calculate the expectation value of an operator Op on Qiskit's simulator with noise present. I am trying to study the impact of various kinds of ...
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What does adding depolarizing error on a Hadamard gate mean mathematically?
I have a quantum circuit as the following picture. Now I add the depolarizing error on the Hadamard gate using the following code in Qiskit.
...
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1
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G-twisted Pauli twirl circuit
Pauli twirls are obtained by taking a unitary $U$, and finding some Pauli gates $P_1, P_2$ such that $P_1 U P_2$. So, for example, one possible twirl of the $S$ gate would be $YSX$.
In the paper ...
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Mathematical justification of postprocessing in QRNG
I have reading about Quantum Random Number Generators (QRNGs), and it seems that usually classical post processing is applied to the initial output of the quantum circuit to:
improve the quality of ...
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Exploiting virtual-$Z_{\theta}$ corrections in QEC
The work done by IBM Researchers to perform virtual-$Z_{\theta}$ gates allowed them to:
achieving zero-time relative phase shifts;
correcting $Z_{\phi}$ errors occurring when applying some gates -- e....
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How many measurements are required to resolve data with a given fidelity?
From Google's quantum supremacy paper
Having found the error rates of the individual gates and
readout, we can model the fidelity of a quantum circuit
as the product of the probabilities of error-...
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Representing 1 qubit pauli-channels as an averaging effect of random rotations in the bloch sphere. Basic literature?
I am looking into 1 qubit pauli channels, e.g. the dephasing channel
$$\mathcal{E}(\rho)=(1-p)\rho+p\sigma_z\rho\sigma_z.$$ I found out it could be represented as
$$\mathcal{E}(\rho)=\int p(\lambda)\...
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What is the explicit form of $T_1$ decay channel?
I see $T_1$ error mentioned in many experimental papers (for example, page $10$ of this paper mentions such a decay.)
How do I model $T_1$ decay theoretically? More concretely, here's my question. Say ...
- 1,251
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Comparing the Erasure and Depolarizing Noise Channels in QEC
Are there any quantum error-correction codes which have been found to exhibit high thresholds for either Pauli-based depolarizing noise or Erasure noise channels, but not for both? Are there reasons ...
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1
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72
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Upper bounding the trace distance between a noisy and noiseless quantum state
Consider a quantum state
$$ \rho = \begin{pmatrix}
\rho_{00} & \rho_{01} \\
\rho_{10} & \rho_{11} \\
\end{pmatrix}. $$
Now, consider the effect of the amplitude damping noise $\mathcal{N}$ of ...
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103
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How can I perform syndrome measurements for both X-type and Z-type stabilizers in Stim?
I would like to simulate the logical error rate of the surface code under depolarizing noise using Stim. The decoder I am using decodes from both X-type and Z-type stabilizer syndrome values. ...
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What is the Stim color_code:memory_xyz circuit executing?
In Stim's color_code:memory_xyz, the all data qubits are first initialized to the |0> state, then the Z-type stabilizer measurement circuit is executed, and ...
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Is there a way to perform two simulations with the same noise in Stim?
I would like to calculate the logical error probabilities of surface codes under depolarizing noise using Stim. In doing so, if all data qubits are initialized to |0>, it is not possible to account ...
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Is it possible to get access to the old noise model from a few months ago for Ibmq backends?
I performed an experiment on a real Ibmq backend, and the results were satisfactory. I now require the simulation of that experiment. The simulation is not sufficiently consistent with the old ...
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1
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How can I determine if the error correction by estimated error results in a logical error in circuit-level noise?
I am trying to simulate the logical error probability of color code under circuit-level noise.
In the code capacity noise and the phenomenological noise, the Pauli errors to the data qubits that occur ...
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1
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How can I extract actual Pauli error in Stim?
I am using a quantum circuit simulator "Stim" to simulate the logical error probability of color code under circuit-level noise.
In the code capacity noise and the phenomenological noise, ...
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Does anybody have the crosstalk profile of the guadalupe system?
Does anyone have the crosstalk profile of the IBM Quantum processor Guadalupe? Or knows how I can get it?
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Custom noise models in Cirq
I want to simulate a quantum circuit using Cirq, with a noise model that defines a certain error rate $e_1$ for single-qubit gates and a certain error rate $e_2$ for 2-qubit gates.
So I know it's ...
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expectation value of a noisy system
I'm trying to find the expectation value of an operator using a noisy circuit and this is the code I found:
...
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0
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Lindblad under time rescaling: Zero noise extrapolation
This question is related to an earlier post Zero noise extrapolation for error mitigation: Meaning of rescaled density matrix, specifically when there is no local hamiltonian evolution
If I have the ...
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Zero noise extrapolation for error mitigation: Meaning of rescaled density matrix, specifically when there is no local hamiltonian evolution
I have a few questions regarding dynamics rescaling for zero noise extrapolation. In the paper Error mitigation for short-depth quantum circuits, in equation (30), they write
We redefine $T \...
2
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1
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280
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How to get a noisy density matrix after partial measurements in Qiskit
I'm trying to study the effect of noise on a quantum system with partial measurements using Qiskit. Suppose I have $N + M$ qubits and I run a quantum circuit and measure $M$ of them. I want to know ...
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Is there any map between Phenomenological Noise Model and Circuit Based Noise Model?
In the phenomenological noise model, we have an approximately 2% error threshold in surface codes. In the circuit-based noise model, the threshold ranges from 0.5% to 0.7%. I'm curious if there's a ...
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2
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Converting $T_1$ and $T_2$ decay rates to noise supported by stim
Stim only supports Pauli noises like DEPOLARIZE1, DEPOLARIZE2, X_ERROR, ...
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0
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Simulation of environment noise in tensor networks
I want to simulate a noisy version of a tensor network efficiently. I do not want to bring noisy gates into the picture and make the "environment" my only noise source. I know the ...
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Is it possible to use fake backends to run Qiskit Runtime primitives?
I have the following code to run an Estimator primitive by using Qiskit Runtime. It computes the expectation value $\langle O \rangle = \langle \psi | O | \psi \...
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Propagation rules for the cross-resonance gate of IBM ($R_{zx}$)
The $R_{zx}$ is the fundamental two-qubit gate supported by IBM processors. I'd like to see how Pauli operators propagate over such a gate.
Other well-known cases are shown in the picture below.
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How relevant is quasiparticle tunneling noise to the T1 of a transmon?
I wish to check how much quasiparticle noise contributes to the relaxation of a transmon qubit since I need to use it for a project.
3
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Simulation files for noisy quantum circuits
For our study with Yosi Rinott and Tomer Shoham we need the following simple data:
Starting with a quantum circuit $C$ on $n$ qubits we need two files:
a) A file of probabilities (or amplitudes) for ...
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noise and classical bits (measurements ) in qiskit
I am using qiskit and LocalNoisePass to add custom noise to the gates. But there is a problem when there are classical bits in the circuits. The localNoisePass give this error
...
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Why my noise model acts different on my VQE circuit compared to a simple circuit
I have created a noise model which uses depolarizing error and I add it using the add to all qubits quantum error command. I also use readout error and add that using the add to all qubits readoute ...
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How to import noise model from IBM qiskit real device?
I am trying to import the noise model of an IBM 'large' device. I don't have access to the devices with more than 7 qubits so it doesn't allow me to import the backend and then do
...
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Why is dual-rail encoding called an error-detecting code for amplitude damping?
Exercise 8.23 : Suppose that a single qubit state is represented by using two qubits, as $|\psi\rangle=a|01\rangle+b|10\rangle$. Show that $\mathcal{E}_{AD}\otimes\mathcal{E}_{AD}$ applied to this ...
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