5 papers
Sample Optimal and Memory Efficient Quantum State Tomography
Yanglin Hu, Enrique Cervero-MartÃn, Elias Theil +2
Quantum state tomography is the fundamental physical task of learning a complete classical description of an unknown state of a quantum system given coherent access to many identic…
Quantum Purity Amplification for Arbitrary Eigenstates and Multiple Outputs
Zhaoyi Li, Elias Theil, Aram W. Harrow +1
Quantum purity amplification (QPA) is the task of coherently transforming copies of a mixed state into high-fidelity copies of a chosen eigenstate. We solve QPA in the general…
An Exponential Sample-Complexity Advantage for Coherent Quantum Inference
Zhaoyi Li, Elias Theil, Aram W. Harrow +1
Standard quantum inference converts quantum data into classical outputs. We study an alternative inference setting in which the desired output is quantum, preserving coherence. Suc…
Classification and implementation of unitary-equivariant and permutation-invariant quantum channels
Laura ManÄinska, Elias Theil
Many quantum information tasks use inputs of the form , which naturally induce permutation and unitary symmetries. We classify all quantum channels that respect bot…
A memory and gate efficient algorithm for unitary mixed Schur sampling
Enrique Cervero-MartÃn, Laura ManÄinska, Elias Theil
We formalize the task of unitary Schur sampling -- an extension of weak Schur sampling -- which is the process of measuring the Young label and the unitary group register of an inp…