Questions tagged [chemistry]
For questions regarding applications of quantum computing and quantum information theory in quantum chemistry or applications of chemistry in quantum computing architecture.
26
questions
2
votes
1answer
36 views
How to improve accuracy of ground energy values from a VQE
Using the Qiskit textbook I have been using a VQE to find the ground state energy of Hydrogen at different interatomic distances on a quantum machine. However, the average energy value I will always ...
1
vote
0answers
51 views
Is there a connection between the definitions of one- and two-particle reduced density matrices?
In quantum chemistry, there are concepts about one-particle reduced density matrix (1-RDM) and similarly, the two-particle reduced density matrix (2-RDM).
Generally, for an $n$ particle wavefunction $|...
3
votes
4answers
57 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
1answer
86 views
Why VQE gives an incorrect ground state energy for a chain of 4 hydrogen atoms?
I am a bit hesitant to ask this very specific question, as I feel other people need not benefit from it. But since I have struggled for a while, and I think I should get some help.
So I am using VQE ...
2
votes
1answer
36 views
How is the Hartree accuracy calculated between the exact and VQE results?
In the Simulating Molecules using VQE section of the Qiskit textbook it states an accuracy of $0.0016$ Hartree between the exact and ...
0
votes
1answer
59 views
What is the convention of indices for the one and two-body integrals in qiskit
I was able to calculate the one and two-body integrals for the H2 with the following code
...
6
votes
0answers
54 views
Impact of ordering Hamiltonian terms for Trotterization
In Trotterization, the typical Hamiltonian considered is:
$$ H = \sum_{p, q} h_{pq} a^{\dagger}_p a_q + \sum_{p, q, r, s} a^{\dagger}_p a^{\dagger}_q a_r a_s $$
Which is then converted into a sequence ...
4
votes
1answer
65 views
What are some current applications of Quantum Computing in drug discovery? Are there any test examples of this?
I am interested in applying the power of Quantum Computing to drug discovery. Although I realize that quantum computing is limited in regards to modeling drug-like compounds and their interactions ...
2
votes
1answer
80 views
VQE jobs do not appear in queue
I am trying to calculate the ground state energy of some simple molecules using 'MolecularGroundStateEnergy' tools in qiskit. When I run the calculations for very small molecules (e.g. H2, HeH+) the ...
1
vote
1answer
67 views
Readout using an NMR spectrum
I'm trying to understand how to read results from an NMR quantum computer.
According to Nielsen and Chuang:
The principal output is the free induction decay signal $$V(t) = V_0\text{Tr}\left[e^{-...
3
votes
1answer
166 views
Modifying Qiskit Hamiltonian
I'm fairly new to the Qiskit API. I was wondering if I could get some assistance with trying to implement our technique of projecting out a new Hamiltonian from the ground-state Hamiltonian. The ...
5
votes
1answer
117 views
Developing quantum circuits for specific quantum chemistry configurations
I am interested in learning more about the following: would it be possible for me to simulate a molecule consisting of copper ions through a quantum circuit?
And if so, can that circuit allow me to ...
4
votes
1answer
48 views
Do we know anything about the computational complexity of the exchange-correlation functional?
Density functional theory is based on the Hohenberg-Kohn (HK) theorems and aims to compute the ground-state many-body wavefunction of a physical material and/or molecules.
To put it simply, the HK ...
6
votes
2answers
726 views
Number of Qubits Required for Simulation of Caffeine and Penicillin Molecules
I recently read this report from BCG, which stated:
For scientists trying to design a compound that will attach itself to,
and modify, a target disease pathway, the critical first step is to
...
3
votes
1answer
51 views
Primer for learning about quantum circuits simulating systems
I am interested in a couple of books or arXiv links to learn how to develop quantum circuits for the purpose of simulating quantum multi-body systems. Moreover, I am interested in learning how to ...
6
votes
1answer
391 views
Defining qubit operator from scratch
I'm a beginner with Qiskit and the Python language at all.
Here is my question:
One of the VQE function arguments is qubit operator (qubitOp).
I saw some examples ...
2
votes
1answer
218 views
What are the rules that map the second-quantized fermionic Hamiltonian into spin-form in OpenFermion?
We can use OpenFermion to get the molecular Hamiltonian in the form of:
$$H = \sum_{pq} h_{pq} a_p^\dagger a_q + \frac12 \sum_{pqrs} h_{pqrs} a_p^\dagger a_q^\dagger a_r a_s$$
and we can also use the ...
3
votes
0answers
111 views
How to apply unitary coupled cluster to a spin problem?
I understand how to apply UCC to a problem formulated in a second-quantized (fermion) form: you start with some state and then create a unitary operator out of single-body (or double-, triple- and so ...
3
votes
0answers
29 views
Can one make NV centred type qubits from analogus materials in the periodic table?
Can one replace Nitrogen with Phosphorus and Carbon with Silicon and so on?
What would be the conditions that would preclude such a realisation? Are there any implemenations so far?
3
votes
1answer
46 views
Rabi oscillations with different energy differences
Please check this Rabi oscillations image1:
Now, let's say I want to create a superposition of E1 and E2, so I started an EM field tuned to a frequency related to E2-E1. But, let's say there is ...
2
votes
0answers
21 views
Hamiltonian of the valence electron of Yb+ ion
Let's say I have chosen the valence electron of Yb+ as my qubit. I want to consider it's hyperfine structure as the two-level energy states.
Are my following assumptions correct?
If the magnetic ...
3
votes
0answers
35 views
Spin precession using a laser
According to Christopher Monroe: "Modular Ion Trap Quantum Networks: Going Big", the hyperfine states of the valence electron in the Yb+ is used as a qubit. I know that we can change the spin ...
4
votes
1answer
176 views
Electronic structure calculations and the Ising model: practical?
I was reading this paper which introduces a mapping from a qubit Hamiltonian to an Ising model. Firstly, the first step of the mapping seems to assume that we know an eigenstate of the system (correct ...
8
votes
1answer
115 views
Quantum chemistry: references
I have heard about Quantum chemistry as one of the main applications of quantum computers. However, I have not found concrete related articles with circuit-implementations for these applications.
...
9
votes
2answers
226 views
Quantum Chemistry and Quantum Computing
Predicting the energy of molecules to high accuracy during the course of a chemical reaction, which in turn allows us to predict reaction rates, equilibrium geometries, transition states among others ...
5
votes
1answer
202 views
What set of quantum logical operations can one use to benchmark spin Hamiltonians?
Chemistry background: In magnetic molecules, it is sometimes the case that one can adjust the time-independent Hamiltonian by chemical design. This means there is freedom to adjust parameters in the ...
