# Qadence A framework for experimenting with analog/digital quantum computing David 'Yoric' Teller 

# Qadence A framework for experimenting with analog/digital quantum computing David 'Yoric' Teller  (not my work)

# About Pasqal - We build qubits!

# About Pasqal - We build qubits! - Quantum computers - Quantum algorithms - Quantum tools - Quantum teaching materials - ...


# Quantum computing? - Compute with qubits, not bits. - Still very much open research.

# Quantum computing? - Compute with qubits, not bits. - Still very much open research. - Hardware - Algorithms - Compilers & tools

# Quantum computing? - Compute with qubits, not bits. - Still very much open research. - Hardware - Algorithms - Compilers & tools - Hype

# Why quantum? - Today's processors fight quantum physics. - Aiming for the next generation(s) of hardware.

# Why quantum? - Today's processors fight quantum physics. - Embrace it! - Aiming for the next generation(s) of hardware.

# Why quantum? - Today's processors fight quantum physics. - Aiming for the next generation(s) of hardware. - Faster? - Much more energy-efficient?

# Why quantum? - Today's processors fight quantum physics. - Aiming for the next generation(s) of hardware. - Also, get out of the current hardware dead end.

# Why quantum? - Today's processors fight quantum physics. - Aiming for the next generation(s) of hardware. - Also, hype.

# Bits 

# Qubits 

# Two flavours - Digital - Analog

# Digital 

# Digital - A program is a _circuit_. - Programming languages exist.

# Digital - A program is a _circuit_. - Programming languages exist. - ... for model hardware.

# Analog 

# Analog - A program is geometry + pulses. - Maps naturally to hardware constraints.

# Analog - A program is geometry + pulses. - Maps naturally to hardware constraints. - ...and to some classes of problems.

# Analog - A program is geometry + pulses. - Maps naturally to hardware constraints. - ... how do you program _that_?

# Analog ![\hat{H}(\Omega, \delta, \phi; t) = \sum_{\text{atom } i}\left( \overbrace{ \frac{\Omega}{2}\left[\cos(\phi) \hat \sigma^x_i - \sin(\phi) \hat \sigma^y_i \right] - \delta \hat n_i }^\text{Programmable laser pulse, global interaction} + \underbrace{\sum_{j<i}\frac{C_6}{|\mathbf r_{ij}|^6} \hat n_i \hat n_{j}}_\text{Programmable register, atom-atom interaction}\right) ](../img/hamiltonian.png)

# Analog - A program is geometry + pulses. - Maps naturally to hardware constraints. - ... how do you program _that_? - no, really?

# Qadence

# Qadence A toolkit designed to: - experiment with Digital + Analog circuits; - simulate or execute circuits;

# Qadence A toolkit designed to: - experiment with Digital + Analog circuits; - learn how to design a hardware-friendly language; - without dealing with laser pulses. - simulate or execute circuits;

# Qadence A toolkit designed to: - experiment with Digital + Analog circuits; - simulate or execute circuits; - _optimize_ circuits wrt constraints.

# Qadence A toolkit designed to: - experiment with Digital + Analog circuits; - simulate or execute circuits; - still not my work 😅.

# Demo time! - [Digital](http://localhost:8888/notebooks/Qadence%20digital.ipynb) - [Solving a problem](http://localhost:8888/notebooks/Qadence%20MaxCut.ipynb) - [Analog](http://localhost:8888/notebooks/Qadence%20analog.ipynb) - [Solving a problem](http://localhost:8888/notebooks/Qadence%20curve%20fitting.ipynb)

# Conclusions

# Summary - A toolkit for exploring quantum circuit design. - On current hardware. - On hypothetical hardware. - Circuit optimization. - Not a programming language.

# Summary - A toolkit for exploring quantum circuit design. - On current hardware. - On hypothetical hardware. - Circuit optimization. - Not a programming language - ...yet

# Future works - Libraries - Domain/algorithm enrichments - Compilation - Reconfigurable registers. - Arbitrary Hamiltonians. - Towards easier programming

# Thanks Actual work by Aleksander Wennersteen, Dominik Seitz, Niklas Heim, João P. Moutinho, Roland Guichard, Vytautas Abramavicius, Gert-Jan Both, Gergana V. Velikova, Anton Quelle, Caroline de Groot, Mario Dagrada, Vincent E. Elfving <first.last>@pasqal.com - https://pasqal-io.github.io/qadence - https://browse.arxiv.org/abs/2401.09915