Quantum 5, 589 (2021). https://doi.org/10.22331/q-2021-11-25-589 We consider the entanglement marginal problem, which consists of deciding whether a number of reduced density matrices are compatible with an overall separable quantum state. To tackle this problem, we […]
Quantum 5, 588 (2021). https://doi.org/10.22331/q-2021-11-25-588 Gleason-type theorems for quantum theory allow one to recover the quantum state space by assuming that (i) states consistently assign probabilities to measurement outcomes and that (ii) there is a […]
Quantum 5, 587 (2021). https://doi.org/10.22331/q-2021-11-24-587 We present two new results about exact learning by quantum computers. First, we show how to exactly learn a $k$-Fourier-sparse $n$-bit Boolean function from $O(k^{1.5}(log k)^2)$ uniform quantum examples for […]
Quantum 5, 586 (2021). https://doi.org/10.22331/q-2021-11-23-586 We present a new tensor network algorithm for calculating the partition function of interacting quantum field theories in 2 dimensions. It is based on the Tensor Renormalization Group (TRG) protocol, […]
Quantum 5, 585 (2021). https://doi.org/10.22331/q-2021-11-22-585 We study the performance of medium-length quantum LDPC (QLDPC) codes in the depolarizing channel. Only degenerate codes with the maximal stabilizer weight much smaller than their minimum distance are considered. […]
Quantum 5, 584 (2021). https://doi.org/10.22331/q-2021-11-18-584 I’ve been building Powerpoint-based quantum computers with electron spins in silicon for 20 years. Unfortunately, real-life-based quantum dot quantum computers are harder to implement. Materials, fabrication, and control challenges still […]
Quantum 5, 583 (2021). https://doi.org/10.22331/q-2021-11-17-583 $textbf{scqubits}$ is an open-source Python package for simulating and analyzing superconducting circuits. It provides convenient routines to obtain energy spectra of common superconducting qubits, such as the transmon, fluxonium, flux, […]
Quantum 5, 582 (2021). https://doi.org/10.22331/q-2021-11-17-582 A large body of recent work has begun to explore the potential of parametrized quantum circuits (PQCs) as machine learning models, within the framework of hybrid quantum-classical optimization. In particular, […]
Quantum 5, 581 (2021). https://doi.org/10.22331/q-2021-11-16-581 We show that the Randomized Benchmarking (RB) protocol is a convolution amenable to Fourier space analysis. By adopting the mathematical framework of Fourier transforms of matrix-valued functions on groups established […]
Quantum 5, 580 (2021). https://doi.org/10.22331/q-2021-11-16-580 The Clifford group is a finite subgroup of the unitary group generated by the Hadamard, the CNOT, and the Phase gates. This group plays a prominent role in quantum error […]
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