Questions tagged [simulation]
For questions about simulating either quantum computers or simulating things on quantum computers.
142
questions
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What is the “sum-over-paths” picture of quantum computing?
In chapter 9 of Scott Aaronson's book Quantum Computing Since Democritus (see online progenitor lecture notes here), he introduces a strange (to me) conceptualization of applying two Hadamard-like ...
1
vote
0answers
50 views
Length / transpilation issues with Grover's algorithm
I would like to discuss the discrepancies between what we see in the simulator versus what we see in the actual running of the code on any IBMQ machine for any qubits at 5 or above. I am doing a final ...
1
vote
1answer
44 views
Computation of qubits with quantum gates using density matrix form
I'm making a quantum circuit with qubits and quantum gates. While I'm doing it, I have some problem with it. My calculation process is below.
As you can see, start qubit is $|0 \rangle$ and after 'X' ...
2
votes
1answer
49 views
Qiskit “statevector_gpu” method not available
I am trying to use the statevector_gpu simulation method in Qiskit Aer (see this page). I installed qiskit-aer-gpu according to ...
1
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1answer
31 views
Qiskit BasicAer simulator options
I usually use Qiskit "Aer" to simulate quantum circuit with several methods such as statevector, density_matrix, ...
1
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1answer
43 views
Qiskit BasicAer & Aer
While I'm simulating grover's algorithm, I found that with BasicAer backend it works well but with Aer it is not. What is the difference between ...
2
votes
3answers
31 views
Where can I get circuits of interest to quantum chemistry to try and simplify?
I am a computer science undergraduate working on a project in simplifying quantum circuits (using the ZX-calculus). I was hoping to try to simplify some circuits of interest rather than randomly ...
2
votes
2answers
163 views
How is a quantum simulator able to simulate a quantum mechanical properties on a classical computer?
I'm confused as to how a classical computer can simulate quantum mechanical properties through the use of classical bits. Why do we need quantum computers if a quantum simulator can do it's job on a ...
3
votes
2answers
75 views
What is the best approach for classically simulating quantum devices?
Now I'm focusing on quantum simulation (especially on classical supercomputers), but I saw there exist so many simulators. Is there any criteria to judge which is the best?
https://www.quantiki.org/...
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1answer
40 views
Inconsistency in Qiskit Aqua CircuitSampler from Operator Flow
I am trying to wrap my head around Qiskit Aqua Operators and I stumbled upon this:
My code
...
1
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1answer
45 views
Why is the lowest energy important to simulate a quantum system?
Quantum computers promise that they will simulate complex quantum systems, and I keep hearing that finding the ground state of that system (using for example Variational quantum eigensolver) is ...
2
votes
1answer
50 views
Why running time of qasm simulator is significantly smaller in comparison with quantum machines?
I ran a 3-qubit measurement circuit on QASM simulator as well as on IBM Q Melbourne, Santiago and Vigo machines. The running time on the simulator is in few milliseconds (400-800) while in the case of ...
-1
votes
2answers
67 views
How to plot histogram using statevector simulator?
I'm trying to run my quantum circuit and plot the simulation result (counts) using the statevector simulator (to avoid 'shot noise'). However, instead of a 2-d histogram, the examples on Qiskit ...
1
vote
1answer
45 views
How can I print out the probability of a certain state in histogram?
This is a simulation I did in my program. I'm hoping to print out the probability of the state $|0001\rangle$ (which is $0.052$), and store this number in a letter (a). How can I do this? Thanks!!
2
votes
2answers
44 views
How to fix “QiskitChemistryError:PySCF is not installed”
I’m trying to simulate LiH using VQE. But I keep getting the error
QiskitChemistryError:PySCF is not installed
And I tried several ways to see whether my driver for the molecule was typed wrong. But ...
0
votes
1answer
36 views
Unable to retrieve result for Job Error during VQE simulation
I am attempting to run a VQE calculation on the 'ibmq_qasm_simulator'. The job is failing with a series of errors caused by:
...
2
votes
1answer
23 views
Any good resources for learning about quantum networks and how to do a simulation of BB84 protocol?
I'm a communication engineering student. And I'm thinking of doing my project on BB84 protocol but I don't know where to start. As a beginner, are there any documents or tutorials about quantum ...
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0answers
24 views
Simulating a Quantum Network over a real Classical Network Using Simulaqron
I'm trying to simulate a quantum network over a real classical network using the Simulaqron framework. I know the documentations says this is possible but I am having trouble finding examples of how ...
7
votes
1answer
91 views
Preparing any superposition of fixed Hamming weight states
There exists a nice way of preparing any superposition (with real amplitudes — this is the case I'm interested in) of states $\{\ldots0001\rangle,\,|\ldots0010\rangle,\,|\ldots0100\rangle,\ldots\}$, ...
1
vote
1answer
60 views
IBMQ_Melbourne Readout error
I am trying to simulate an experiment on IBM's melbourne quantum computer and here are the results
Qasm simulator :
ibmq_16_melbourne:
error
why is there such high probability of unwanted states i....
1
vote
2answers
115 views
Why should we use density matrices to simulate quantum systems with noise?
Why we should use density matrices to simulate quantum systems with noise?
I found that the any QEC circuit is included by some quantum gates just like normal cases, which means the state vector can ...
0
votes
1answer
113 views
How the simulator work?
Recently I focused on how to simulate in classical computer, and I found Qiskit offers qasmsimulator and statevector simulator. ...
1
vote
1answer
61 views
A question about how does the single qubit gate simulated in simulator?
I have found the procedure of simulation process as this picture :
Image reference. So in the low-level compilers, all single-qubit gates are approximated by the universal gate set (CNOT, H, T, S).
...
1
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1answer
30 views
What would be the difference between using qsharp library on python vs learning the Q# langauge?
One difference of course is the syntax. But I'm guessing the idea is eventually quantum computers will be able run Q#, whereas now it uses simulations. Will code written in Python with the qSharp ...
1
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2answers
83 views
Why do I get positive amplitudes when I create a qiskit StateVectorCircuit from only negative amplitudes?
I am using amplitude encoding to encode my features in a quantum circuit. With this I expect to encode e.g. 32 features in five qubits.
For the encoding I use qiskit's ...
4
votes
2answers
192 views
How does a classical computer simulate nonclassical correlations?
This may be a dumb question, if so please forgive me, it is late at night.
I have learned that a classical computer can simulate a quantum computer in exponential time and space, but classical ...
1
vote
1answer
38 views
A question about how to emulate quantum states and computation on classical computer
I have understood the concept of "universal quantum gates" in real quantum computer, and the quantum gates and states can be emulated as matrix in classical computer, and the matrix operation can be ...
3
votes
2answers
100 views
How to run an approximate simulation, and why
I'm looking at the Qiskit getting started documentation, https://qiskit.org/documentation/getting_started.html. They create a quantum circuit and run an approximate simulation on it 1000 times:
Why ...
1
vote
0answers
48 views
How to turn off multiprocessing in TensorFlow Quantum
Some background: I'm currently running the same training algorithm with a classical neural network and a quantum circuit, respectively. The NN is implemented in Keras with a TensorFlow backend, the ...
0
votes
1answer
71 views
Is it a good idea to publish a research paper about the simulation of BB84 protocol?
I'm an engineering student. As my end of year project I've simulated BB84 protocol using simulaqron(python). I'm thinking about publishing a paper about this simulation.
I haven't published any ...
2
votes
0answers
129 views
What is the usefulness of the Suzuki-Trotter formula?
I can't seem to wrap my head around the suzuki-trotter formula. I have seen This answer but I am still confused of the applicability of the formula. Let me explain:
As I understand it Trotterization ...
4
votes
1answer
54 views
Resource recommendation on quantum simulations
I would like to know more about quantum simulations, so as to start on a few standard physical models (maybe particle in a box, harmonic oscillator, etc.) and then build up on more complex things. But ...
3
votes
1answer
141 views
What are the biggest obstacles currently preventing us from solving real world problems defined in terms of quantum simulation?
Quantum simulation (also referred to as Hamiltonian simulation) is defined as follows:
In the Hamiltonian simulation problem, given a Hamiltonian $H$ ($2^n \times 2^n$ hermitian matrix acting on $n$...
3
votes
1answer
100 views
Problem with building quantum circuit for Hamiltonian operation
In the book, Nielsen and Chuang, there is a section on quantum simulation of the quantum search algorithm. Hamiltonion operator is defined as follows-
$$
H = |x\rangle\langle x| + |\psi\rangle\langle\...
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0answers
26 views
Can We Currently Import Quantum Datasets (Datasets Containing Quantum Data) Onto NISQ-era Quantum Computers?
I'm still investigating the TFQ whitepaper.
In one section of the paper, the authors say this with respect to Quantum Datasets
In general, [a quantum dataset] might come from a given black-box ...
2
votes
1answer
104 views
Question Regarding Simulating Hamiltonian With Quantum Circuit
There have been a few other questions about this section of Nielsen and Chuang, but when working through the output of the circuit, there are some inconsistencies that are probably due to some mistep/...
0
votes
1answer
101 views
Can every process in nature be simulated by a Turing Machine or a quantum computer?
Given any initial condition or value A, A leads to B after a procedure of physics or nature P. Now is there any turing machine or quantum computer that can simulates P,converting A into B? In other ...
1
vote
1answer
49 views
Results of SAT on the Qiskit simulator
I computed SAT formula with the Grover search algorithm on the Qiskit simulator with default parameters, but I don't understand why the incorrect solutions don't have a probability of 0?
The SAT ...
1
vote
1answer
59 views
A question about quantum circuit simulation on PC
In classical logic circuit consisting of AND, OR and others, common gates can be realized by electrnic signal. Each time cycle can run a function unit like the picture below.
Now I have read many ...
6
votes
1answer
118 views
What did exactly Google do in simulating a random quantum circuit on a classical computer in supremacy experiment?
I've been working on Google quantum supremacy paper for quite some time now and I have a problem in understanding how exactly they simulate their actual random quantum circuit on a classical computer.
...
4
votes
5answers
178 views
Does a classical computer really require $2^n$ complex numbers to represent the state of $n$ qubit quantum computer?
One often reads that the key reason why classical computers (probabilistic or deterministic) are unable to simulate quantum algorithms such as Simon's or Shor's efficiently is that a classical ...
2
votes
1answer
249 views
How Mature is the Tensorflow Quantum Library [closed]
Where does The Tensorflow Quantum ( TFQ ) library fall on it's maturity curve.
In other words can we currently leverage the TFQ ...
1
vote
0answers
59 views
What Are The Most Promising Real-World Applications For Quantum Machine Learning
I know this has been asked before in different ways, however, I am interested in something with a degree of clarity and focus not found in other questions.
What I am looking to get is a list of the ...
5
votes
3answers
132 views
Does Planck's constant have any role in quantum computing?
I am new to the area of quantum computing, but as I study it I can't help wonder about the role of the Planck's constant. When one studies quantum mechanics one often finds statements that quantum ...
2
votes
2answers
63 views
Ansatz state for finding the lowest eigenvalue of a $2^n\times 2^n$ real matrix using VQE
I would like to find the lowest eigenvalue of a $2^n\times 2^n$ real matrix $H$ using the VQE procedure. The measurement part is simple — I just expand $H$ in a sum of all possible $n$-qubit Pauli ...
1
vote
1answer
43 views
Rotation of multi-body interaction in quantum circuit
In quantum circuit, how do you implement the rotation of multi-body interaction, such as $e^{-i\theta\sigma_z^1\sigma_z^2\sigma_z^3}$? I already know the case of less than two-body interaction, but I ...
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0answers
30 views
How to get the $T1$ specs for the Rigetti's quantum processor (Aspen 7)
I am trying to find the $T1$ coherence time for different qubits of Rigetti's quantum processor (Aspen 7) using Python. I tried using Specs() but encountered an ...
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0answers
42 views
Why Alice and Bob don't get the same result when they measure in the same basis?
I'm simulating the BB84 protocol using simulaqron. My
problem is that when Alice and Bob measure in the same basis, they
don't get the same result.
How can I fix this error?
.
BB84.py
...
1
vote
2answers
189 views
Entanglement Swapping Circuit
I implemented 2 versions of the entanglement swapping circuit in IBM Q. One is using classical measurement to control X, Z gates. Another is just us C-NOT and Controlled-Z. They should be equivalent. ...
2
votes
0answers
44 views
“$W_n$ state” in Bravyi-Kitaev encoding
For a particular simulation, I need the initial (physical) state of the QC to represent the equal superposition of all single-occupancy fermionic second-quantized states. In Jordan-Wigner encoding, I ...
