Summary:
Focus: AI techniques for modeling quantum matter/materials
Materials the behavior of which is government by a many-body quantum state
Behavior is collective, not single particle
Very sensitive to values of external knobs
Ex: superconductors, topological materials, quantum magnets
Physics:
Wavefunction is a complex valued vector function in an exponentially large space
Evolves over time
Need ensemble of wavefunctions to finite temperature equilibrium state
Though, not all phenomena can be described as equilibrium states
Task:
Need to design a material from given set of chemicals with set of desired properties
Many forward modeling challenges
Exponential wavefunction statespace
Relevant latent variables are unknown and emergent
Never observe wavefunction directly
Traditional forward models require strong inductive bias (results in errors where bias is incorrect)
Data is invaluable since the inverse modeling problem (given data, infer best model) is very challenging and data intensive
A representation learning problem where we need to ingest diverse datasets that collectively constrain the behavior space of the physics into a common representation that can be used to constrain models
Representation Learning
Quantum attention networks for state characterization
Scenario: state space of many binary qubits
Given a fine number of samples, summarize them in the most informative representation
Approach: classification problem
Volume law vs area law state
Topological vs trivial state
Shallow circuit vs deep circuit
Model looks at correlation in the moments; has access to higher order moments without explicitly representing them
Exploit permutation invariance in the samples by training model on random batches of observations
X-TEC for X-Ray diffraction
Goal: infer temperature/disorder from X ray images of materials
Infer time series and its phase transition across temperature thresholds
Enables experimentalists to collect data at the key phase transition temperature range
GPTc: Gaussian process Tc Predictor
Accumulated Heterogeneous Data
Gather materials structure information across the literature
Molecular structure is the key differentiator for the differences in physical behavior beyond chemical composition
Elemental features: electron affinity, electronegativity, ionization potential, covalent radius, atomic weight, column, # valence s/p/d e
Considering many candidate 2nd order features (e.g. interatomic distance)
Using ML to evaluate various features by using them as inputs to an ML model to predict observable properties
Identify which features are useful
Using Gaussian Processes to use histograms as features
Was able to predict superconductivity and transition temperature of a new material where it was previously unknown