We study various methods to generate ensembles of random density matrices of a fixed size
N, obtained by partial trace of pure states on composite systems. Structured ensembles of�…

A cornerstone of quantum mechanics is the characterization of symmetries provided by
Wigner's theorem. Wigner's theorem establishes that every symmetry of the quantum state�…

We study the storage capacity of quantum neural networks (QNNs), described by completely
positive trace preserving (CPTP) maps acting on an N-dimensional Hilbert space. We�…

The two-time measurement scheme is well studied in the context of quantum fluctuation
theorem. However, it becomes infeasible when the random variable determined by a single�…

We propose an extended quantum theory, in which the number K of parameters necessary
to characterize a quantum state behaves as fourth power of the number N of distinguishable�…

In this work, we present a lower bound on the quantum Fisher information (QFI) which is
efficiently computable on near-term quantum devices. This bound itself is of interest, as we�…

We provide a universal construction of the category of finite-dimensional C*-algebras and
completely positive trace-nonincreasing maps from the rig category of finite-dimensional�…

In this work, we extend the idea of quantum Markov chains (Gudder in J Math Phys 49 (7):
072105 [3]) in order to propose quantum hidden Markov models (QHMMs). For that, we use�…

We investigate the set (a) of positive, trace preserving maps acting on density matrices of
size N and a sequence of its nested subsets: the sets of maps which are (b)�…

Forgetfulness is a common feature of nature. Moreover, without forgetfulness, repeatability
would be impossible. Despite this, small systems constantly leak information about their�…