In this repository we have the code used to explore and model several possible circuit designs for a future charge tomography measurement. This code was developed for a MSc research project entitled "Simulating Superconducting Circuit for Charge-Basis Tomography".

To get started clone the repository and install the required packages by running

pip install -r requirements.txt

from the root of the repository directory.

The code is divided between circuit models and analytics, with the vast majority of focus put into circuit models. Circuit models come in four categories:

• Directly Coupled Circuit
  • Probe-target qubits coupled via a capacitor
  • Longitudinal and transversal coupling is explored
  • Tunability of the qubits is explored
  • Impact of alpha dispersion (variability in probe qubit junctions) is explored
  • Bayesian optimisation of the circuit parameters is implemented
• Indirectly (Resonator) Coupled Circuit
  • Probe-target qubits coupled via a resonator
  • Longitudinal and transversal coupling is explored
  • Impact of alpha dispersion (variability in probe qubit junctions) is explored
  • Impact of charge state cut-off is inspected
• Flux Qubit
  • Simple model of a flux qubit
  • Qubit spectrum is plotted for a range of gate charges
• C-Shunt Circuit
  • Single three junction capacitively shunted qubit
  • Limited time spent on this circuit so far

The circuit model notebooks typically have a system class which describes characterises the quantum system, they then use this class to inspect properties of the circuit in certain parameter regimes. The simplest example of such a system class is in the flux qubit notebook.

• The superconducting circuit companion -- an introduction with worked examples
  S. E. Rasmussen, K. S. Christensen, S. P. Pedersen, L. B. Kristensen, T. Bækkegaard, N. J. S. Loft, N. T. Zinner

• A Quantum Engineer's Guide to Superconducting Qubits
  Philip Krantz, Morten Kjaergaard, Fei Yan, Terry P. Orlando, Simon Gustavsson, William D. Oliver

• Circuit-QED-based scalable architectures for quantum information processing with superconducting qubits
  P.-M. Billangeon, J. S. Tsai, and Y. Nakamura

• Synthesizing arbitrary quantum states in a superconducting resonator
  Max Hofheinz, H. Wang, M. Ansmann, Radoslaw C. Bialczak, Erik Lucero, M. Neeley, A. D. O'Connell, D. Sank, J. Wenner, John M. Martinis & A. N. Cleland

• Observation of quantum state collapse and revival due to the single-photon Kerr effect
  Gerhard Kirchmair, Brian Vlastakis, Zaki Leghtas, Simon E. Nigg, Hanhee Paik, Eran Ginossar, Mazyar Mirrahimi, Luigi Frunzio, S. M. Girvin & R. J. Schoelkopf