From the 1 of 7 linked papers with an AI index.
7 papers
The Keyl-Werner algorithm is not optimal for spectrum estimation
Angelos Pelecanos, Jack Spilecki, Ewin Tang +1
The paper presents a new algorithm that estimates the eigenvalues of a quantum state using fewer copies than the traditional Keyl‑Werner method, achieving constant error with O(d^2…
Learning the structure of open quantum systems
Laura Lewis, Ewin Tang, John Wright
We design an algorithm for learning the coefficients of an -qubit constant-local Lindbladian to error with total evolution time,…
Conjugate queries can help
Ewin Tang, John Wright, Mark Zhandry
We give a natural problem over input quantum oracles which cannot be solved with exponentially many black-box queries to and , but which can be solved with const…
Are controlled unitaries helpful?
Ewin Tang, John Wright
Many quantum algorithms, to compute some property of a unitary , require access not just to , but to , the unitary with a control qubit. We show that having access to $cU…
Amplitude amplification and estimation require inverses
Ewin Tang, John Wright
We prove that the generic quantum speedups for brute-force search and counting only hold when the process we apply them to can be efficiently inverted. The algorithms speeding up t…
Mixed state tomography reduces to pure state tomography
Angelos Pelecanos, Jack Spilecki, Ewin Tang +1
A longstanding belief in quantum tomography is that estimating a mixed state is far harder than estimating a pure state. This is borne out in the mathematics, where mixed state alg…