We identify five selected open problems in the theory of quantum information, which are
rather simple to formulate, are well studied in the literature, but are technically not easy. As …

We derive fundamental bounds on the maximal achievable precision in multiparameter
noisy quantum metrology, valid under the most general entanglement-assisted adaptive …

The ultimate precision in quantum sensing could be achieved using optimal quantum probe
states. However, current quantum sensing protocols do not use probe states optimally …

We present a hybrid quantum-classical variational scheme to enhance precision in quantum
metrology. In the scheme, both the initial state and the measurement basis in the quantum …

The estimation of more than one parameter in quantum mechanics is a fundamental
problem with relevant practical applications. In fact, the ultimate limits in the achievable …

This work compares the performance of single-and two-qubit probes for estimating several
phase rotations simultaneously under the action of different noisy channels. We compute the …

We address the use of asymptotic incompatibility (AI) to assess the quantumness of a
multiparameter quantum statistical model. AI is a recently introduced measure which …

Polarization is one of light's most versatile degrees of freedom for both classical and
quantum applications. The ability to measure light's state of polarization and changes …

This paper reviews Holevo's contributions to quantum information theory during the 20
century. At that time, he mainly studied three topics, classical-quantum channel coding …

One of the fundamental tasks in quantum metrology is to estimate multiple parameters
embedded in a noisy process, ie a quantum channel. In this paper, we study fundamental …