4 papers · 1 filter
Learning Hamiltonians in the Heisenberg limit with static single-qubit fields
Shrigyan Brahmachari, Shuchen Zhu, Iman Marvian +1
Learning the Hamiltonian governing a quantum system is a central task in quantum metrology, sensing, and device characterization. Existing Heisenberg-limited Hamiltonian learning p…
Optimal Qubit Purification and Unitary Schur Sampling via Random SWAP Tests
Shrigyan Brahmachari, Austin Hulse, Henry D. Pfister +1
The goal of qubit purification is to combine multiple noisy copies of an unknown pure quantum state to obtain one or more copies that are closer to the pure state. We show that a s…
A fixed-point algorithm for matrix projections with applications in quantum information
Shrigyan Brahmachari, Roberto Rubboli, Marco Tomamichel
We develop a fixed-point iterative algorithm that computes the matrix projection with respect to the Bures distance on the set of positive definite matrices that are invariant unde…
Quantum contextual bandits and recommender systems for quantum data
Shrigyan Brahmachari, Josep Lumbreras, Marco Tomamichel
We study a recommender system for quantum data using the linear contextual bandit framework. In each round, a learner receives an observable (the context) and has to recommend from…