S. R. Jha, S. Chowdhury, M. Hays, J. A. Grover, W. D. Oliver
Docs: equs.github.io/qcsys
Community Discord: discord.gg/frWqbjvZ4s
Built on JAX, qcsys
presents a scalable way to assemble and simulate systems of quantum circuits.
Recommended: As this is a rapidly evolving project, we recommend installing the latest version of qcsys
from source as follows:
pip install git+https://github.com/EQuS/qcsys.git
After installing qcsys
, update the jaxquantum
dependency to its latest version from source:
pip install git+https://github.com/EQuS/jaxquantum.git
If you are interested in contributing to the package, please clone this repository and install this package in editable mode after changing into the root directory of this repository:
pip install -e ".[dev]"
This will also install extras from the dev
flag, which can be useful when developing the package. Since this is installed in editable mode, the package will automatically be updated after pulling new changes in the repository.
After installing qcsys
, update the jaxquantum
dependency to its latest version from source:
pip install git+https://github.com/EQuS/jaxquantum.git
qcsys
is also published on PyPI. Simply run the following code to install the package:
pip install qcsys
For more details, please visit the getting started > installation section of our docs.
Here's an example on how to use qcsys
:
import qcsys as qs
# Devices ----
_, Ec_a, El_a = qs.calculate_lambda_over_four_resonator_zpf(3, 50)
resonator = qs.Resonator.create(
10,
{"Ec": Ec_a, "El": El_a},
N_pre_diag=10,
)
Ec_q = 1
El_q = 0.5
Ej_q = 8
qubit = qs.Fluxonium.create(
25,
{"Ec": Ec_q, "El": El_q, "Ej": Ej_q, "phi_ext": 0.47},
use_linear=False,
N_pre_diag=100,
)
# System ----
g_rq = 0.3
devices = [resonator, qubit]
r_indx = 0
q_indx = 1
Ns = [device.N for device in devices]
a0 = qs.promote(resonator.ops["a"], r_indx, Ns)
a0_dag = qs.promote(resonator.ops["a_dag"], r_indx, Ns)
q0 = qs.promote(qubit.ops["a"], q_indx, Ns)
q0_dag = qs.promote(qubit.ops["a_dag"], q_indx, Ns)
couplings = []
couplings.append(-g_rq * (a0 - a0_dag) @ (q0 - q0_dag))
system = qs.System.create(devices, couplings=couplings)
system.params["g_rq"] = g_rq
Es, kets = system.calculate_eig()
# chi ----
χ_e = Es[1:, 1] - Es[:-1, 1]
χ_g = Es[1:, 0] - Es[:-1, 0]
χ = χ_e - χ_g
# kerr ----
# kerr[0,n] = (E(n+2, g) - E(n+1, g)) - (E(n+1, g) - E(n, g))
# kerr[1,n] = (E(n+2, e) - E(n+1, e)) - (E(n+1, e) - E(n, e))
K_g = (Es[2:, 0] - Es[1:-1, 0]) - (Es[1:-1, 0] - Es[0:-2, 0])
K_e = (Es[2:, 1] - Es[1:-1, 1]) - (Es[1:-1, 1] - Es[0:-2, 1])
χ, K_g, K_e
Core Devs: Shantanu A. Jha, Shoumik Chowdhury
This package was initially developed in early 2023 to aid in the design of a superconducting circuit device made for bosonic quantum error correction. This package was also briefly announced to the world at APS March Meeting 2023. Since then, this package has been open sourced and developed while conducting research in the Engineering Quantum Systems Group at MIT with invaluable advice from Prof. William D. Oliver.
Thank you for taking the time to try our package out. If you found it useful in your research, please cite us as follows:
@software{jha2024jaxquantum,
author = {Shantanu R. Jha and Shoumik Chowdhury and Max Hays and Jeff A. Grover and William D. Oliver},
title = {An auto differentiable and hardware accelerated software toolkit for quantum circuit design, simulation and control},
url = {https://github.com/EQuS/jaxquantum, https://github.com/EQuS/bosonic, https://github.com/EQuS/qcsys},
version = {0.1.0},
year = {2024},
}
S. R. Jha, S. Chowdhury, M. Hays, J. A. Grover, W. D. Oliver. An auto differentiable and hardware accelerated software toolkit for quantum circuit design, simulation and control (2024), in preparation.
This package is open source and, as such, very open to contributions. Please don't hesitate to open an issue, report a bug, request a feature, or create a pull request. We are also open to deeper collaborations to create a tool that is more useful for everyone. If a discussion would be helpful, please email shanjha@mit.edu to set up a meeting.