Expected release
Q2 2022A computer-aided design tool for quantum-technology hardware.
QTCAD
A computer-aided design tool for quantum-technology hardware.
Who are the customers
using QTCAD?
Experimental physicists and quantum engineers
Gain a microscopic understanding of latest experiments using finite-element simulations and predict the performance of next-generation quantum devices.
Theoretical physicists
Validate analytic models against realistic finite-element simulations accounting for full device geometry and perform numerical experiments to test your latest ideas in quantum device design, quantum-computing architecture, quantum control, and more.
Benefits
QTCADSpecifically designed for spin qubits
QTCAD solves for quantities relevant to the analysis of spin-qubit systems. These include confined electron or hole eigenenergies, envelope functions, many-body energies and chemical potentials, charge stability diagrams, Rabi oscillations, and more.
Arbitrary 2D and 3D geometry
Produce a CAD model for any device of interest and its corresponding first or second-order Lagrange finite-element mesh using Gmsh, and import it into QTCAD to define and run simulations.
Using QTCAD is convenient and easy
Use our Python-based device editing UI to import layouts directly from your GDS file, and specify your heterostructure stack along the growth direction. Our flexible Python API allows users to define and launch a simulation in a few lines of code, and seamlessly integrate with third-party software for data visualisation and analysis, or even with other Python-based software from the quantum ecosystem (e.g. QuTiP) .
Adaptive meshing
Thanks to our adaptive meshing procedure, QTCAD goes far beyond commercially available TCAD software by predicting the electrostatic properties of spin qubits at cryogenic temperatures (below 1 K)
Download the QTCAD leaflet to get a summary of the software features!
QTCAD can import the gate geometry directly from the layout used in device fabrication.
The conduction band edge resulting from the gate pattern specified in the layout.
Wave function of the first excited state of an electron confined by the gates.
Charge stability diagram used to demonstrate experimentally that a quantum dot operates in the single-electron or single-hole regime.
Valley coupling in silicon-based spin-qubit devices.
Rabi oscillations for a spin qubit under electric-dipole spin resonance accounting for realistic device geometry.
Features
QTCADDescription
QTCAD (Quantum-Technology Computer-Aided-Design) is a finite-element (FEM) simulator used to predict the performance of spin-qubit devices before their production. QTCAD simulations can lead to huge savings in both time and money since they allow users to explore many design scenarios before their implementation in the lab.
Flexible, scriptable, and user-friendly interface
Gated geometries can be imported directly from standard layout (.gds) files used to design integrated circuits [layout.png]. Heterostructure stacks are defined through our simple Python API. This approach captures the geometry of most gated quantum dots. For expert users, arbitrary 2D and 3D geometries and their corresponding mesh can be defined and customized at will using Gmsh.
Electrostatics at cryogenic temperature
QTCAD’s non-linear Poisson solver can predict the confinement potential of quantum dots in semiconductor nanostructures under split gates. QTCAD is designed to converge at sub-Kelvin temperatures in many practical spin-qubit designs. Low-temperature convergence is notoriously difficult with other currently available TCAD software.
Schrodinger solvers
QTCAD’s Schrödinger solver calculates the wave functions of electrons or holes in realistic confinement potentials. These confinement potentials are determined by applying QTCAD’s non-linear Poisson solver to specific device geometries. Thus the computed wavefuntions can be used to predict if a given candidate device can host bound states.
Many-body physics
QTCAD can assemble and exactly diagonalize the many-body Hamiltonian for few-electron or few-hole systems under quantum confinement using a truncated basis built from real-space single-body eigenfunctions of the device. This approach yields accurate chemical potentials and addition-energy spectra for realistic quantum dots accounting for the Coulomb interaction between confined electrons or holes.
Transport physics
Our master equation solver leverages QTCAD’s many-body physics capabilities to calculate the current flowing through quantum-dot systems in the sequential tunneling regime. This enables the treatment of Coulomb blockade and the prediction of charge stability diagrams used to demonstrate the few-electron or few-hole regime in experiments.
Valley-splitting physics
For silicon-based devices, lifting the valley degeneracy is a vital step to isolate well-defined qubit eigenstates. QTCAD includes a module that calculates valley splitting due to sharp heterostructure interfaces using matrix elements in the basis of Bloch states calculated with our atomistic simulation software RESCU.
Gate fidelity for realistic device geometries
Ultimately, QTCAD determines the system Hamiltonian, accounting for realistic device geometry. Once the system Hamiltonian is known, qubit time-evolution can be evaluated using third-party time-dependent Schrödinger solvers (e.g., QuTiP). In this figure, we show Rabi oscillations for a spin-qubit device under electric-dipole spin resonance. We account for a realistic inhomogeneous magnetic field, and for the precise geometry of electric fields acting on the quantum dot due to applied and charge-noise-induced gate potentials.
Multiscale platform
Interface with our large scale DFT software RESCU to calculate material parameters that enter the k.p theory.
Cross-platform implementation
QTCAD can easily be deployed on Linux, MacOS, and Windows machines, on personal computers and clusters alike.
What's new ?
QTCAD is currently in beta testing phase: we invite you to join us to collaborate and contribute in the coming months to prepare version 1.0 release in May 2022. We will review your research group’s profile and respond promptly upon your application. Thank you very much in advance.
Current beta version of QTCAD is 0.7.0.