Christian Pratt

Fourth year physics Ph.D. candidate
Complexity Sciences Center at UC Davis
Advisor: Prof. Jim Crutchfield

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Research

I am broadly interested in the fundamental physics of computation, and how it can help us build faster and more energy-efficient computing systems.

One way to understand the physics of computation is to investigate the physics of storing and processing information; I am applying dynamical systems theory and nonequilibrium thermodynamics to address this. Specifically, my research explores how classical computations are performed with the metastable potential energy landscapes that are generated by superconducting devices.

Papers

Controlled Erasure as a Building Block for Universal Thermodynamically-Robust Superconducting Computing

Christian Z. Pratt, Kyle J. Ray, and James P. Crutchfield

Preprint 

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We introduce the Control Erasure (CE) protocol, which generalizes the Landauer information erasure protocol to an effective two-dimensional potential energy landscape.

Performing a CE involves dynamically changing the landscapes' energy minima---corresponding to the landscape's darker purple colors---in order to control what information is erased or stored. An example CE involves erasing the yellow particle into the cyan particle's location, while storing the silver and pink particles within their respective minima.

Executing successive CEs can lead to performing a NAND gate---an irreversible universal logic gate that is commonly used to construct modern computing architectures. We show how to carry out a NAND gate with a device created by inductively coupling two superconducting quantum interference devices (SQUIDs): This device can serve as a computationally fast and energy efficient universal computing substrate!


Extracting Equations of Motion from Superconducting Circuits

Christian Z. Pratt, Kyle J. Ray, and James P. Crutchfield

Preprint 

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Previously, the network theory approach to analyzing superconducting circuits had limitations, such as only being able to consider at most one linear inductor per circuit loop. We void this assumption and address its consequences, and by doing so, we extended this approach to be able to handle more complicated superconducting circuits.

As an example, we derived the potential energy potential surface generated by a device constructed from two inductively-coupled SQUIDs. This landscape will serve as a test-bed for constructing energy efficient universal logic gates, and investigating their thermodynamic performance.

Recorded Talks

Controlled Erasure as a Building Block for Universal Thermodynamically-Robust Superconducting Computing

Complexity Sciences Center
Aug. 14th, 2024

Video   

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Technical seminar about the paper in the talk's title; its focus was to build up the intuition required for understanding the paper from scratch via figures and animations.

For example, by showing how bifurcation theory can be used to understand the the Landauer protocol, this geometric perspective significantly helps with understanding more general information erasure protocols. Here, blue (yellow) stable (unstable) fixed points are both created and annihilated throughout the protocol.


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