Core-level spectroscopy provides valuable information about the local chemical environment of atoms in molecules by probing core-electronic structure whereas valence-level spectroscopy offers valuable insight into hybridization and bonding via valence-electronic structure. Despite their similarity, modeling core-electronic structure is challenging owing to large orbital-relaxation effects...
Quantum statistical models (i.e., families of normalized density matrices) and quantum measurements (i.e., positive operator-valued measures) can be regarded as linear maps: the former, mapping the space of effects to the space of probability distributions; the latter, mapping the space of states to the space of probability distributions. The images of such linear maps are called the testing...
A giant atom is a quantum emitter that can be coupled to the field non-locally at a set of coupling points [1]. Such a new generation of emitters can nowadays be implemented in circuit QED setups, where some spectacular effects - unachievable with normal atoms - have already been observed. One of these is the possibility to enable chiral (i.e. fully uni-directional) emission upon proper...
In the previous work Rhy. Rev. Lett 126, 063601, we have established a general framework for studying vacancy-like dressed state (VDS) in a generic photonic bath coupled to a normal atom. Here we extend this theory to giant-atom case. We point out that only if a giant atom is coupled to a bath whose energy spectrum possess chiral-symmetry (not necessarily transitionally invariant) and the...
Classical shadows are a powerful method for learning many properties of quantum states in a sample-efficient manner, by making use of randomized measurements. Random local Pauli measurements [1] and shallow shadows [2–4] provide optimal protocols for estimating expectation values of local observables.
On the contrary, the Clifford global-twirling protocol [1] is optimal for estimating global...
Josephson junctions are one of the fundamental building blocks of superconducting quantum devices. With applications ranging from circuit quantum electrodynamics experiments to quantum information processing and quantum sensing, reliable and reproducible devices, and related microfabrication processes, represent a corner stone for every experimental group in the field. There are different...
This study is concerned with the investigation of the continuity of Quantum Fisher Information (QFI) between two states, one experimentally generated , σ=(σ,∂_x σ), and one theoretically derived, ρ=(ρ,∂_x ρ), in different systems such as qubits, exponential density matrices and noise-free quantum dynamics [1, 2, 3, 4].
In quantum parameter estimation, the QFI exhibits universal continuity,...
We investigate the performance of a one dimensional dimerized XY chain as a quantum battery. Such integrable model shows a rich quantum phase diagram which emerges through a mapping of the spins into auxiliary fermionic degrees of freedom. We consider a charging protocol relying on the double quench of an internal parameter, notably the strength of the dimerization. Within this picture we...
Generating bipartite entanglement in quantum computing technologies is widely regarded as a pivotal benchmark. However, multipartite entanglement can appear when solving a complicated optimization problem where the correlation between multiple qubits is beneficial. Understanding whether such entanglement contributes to achieving a feasible solution is crucial from both algorithmic and hardware...
The ground-state of an artificial atom coupled to quantized modes in the Ultra-Strong Coupling regime is entangled and contains an arbitrary number of virtual photons.
The problem of their detection, raised since the very birth of the field, still awaits experimental demonstration despite the theoretical efforts in the last decade.
In a recent work [1] it has been shown that experimental...
We theoretically study how the peculiar properties of the vacuum state of an ultra-strongly coupled system can affect basic light-matter interaction processes. In this unconventional electromagnetic environment, an additional emitter no longer couples to the bare cavity photons, but rather to the polariton modes emerging from the ultra-strong coupling, and the effective light-matter...
In recent cold atom experiments, the utilization of internal degrees of freedom as synthetic dimensions has enabled the simulation of higher-dimensional systems. Specifically, magnetic quantum numbers have been employed to transform a 1D chain of atoms into a synthetic 2D lattice, resulting in the realization of an integer quantum Hall state. However, this configuration introduces highly...
Characterizing the effects of the interaction between quantum systems and their environment is a key challenge in the development of Quantum Technologies. Among the several possibilities, classifying whether the noise is correlated and Markovian has important implications on the dynamics of the system. In this work we consider the simplest quantum network in which correlations can be...
Abstract
The control of superconducting qubits demands advanced instruments and software capable of handling rapid pulses with arbitrary waveforms across microwave frequencies. Traditionally, achieving such precision involved up and down-conversion techniques, merging lower-frequency pulses with higher-frequency tones. This approach often requires multiple instruments per qubit,...
In recent years, the investigation of quantum systems out of equilibrium contributed to the advancement of quantum thermodynamics. In particular, the study of quantum batteries, small quantum mechanical systems able to temporarily store energy and further release it on-demand, recently emerged as a fast-growing subject in this field.
In this framework we have characterized the performances...
Negatively charged Nitrogen-Vacancy (NV-) colour centre in diamond is a well-known and characterized point defect with notable properties such as photostable bright fluorescence and spin states that can be initialised and read out, making it of great appeal for quantum technology applications.
Specifically, the latter can benefit from forming NV- defects in the proximity of the diamond...
In this work, a direct quantum implementation of the Doktorov formulae for calculating the vibronic
spectrum of molecules under the harmonic approximation is presented. The classically hard
problem of estimating the Franck-Condon (FC) factors is solved by using the Duschinsky matrices
as the only input via the Doktorov quantum circuit. This approach offers the advantage of avoiding
basis...
Abstract
Superconducting quantum circuits stand out as a prominent platform for quantum computers. The most diffused qubit design is the transmon qubit, a type of charge qubit that operates at a significantly different ratio of Josephson energy ($E_J$) to charging energy ($E_C$). This unique feature exponentially reduces the sensitivity to $1/f$ charge noise without increasing the...
The purpose of this work is to use a Quantum Annealer (QA) to solve the homogeneous Bethe-Salpeter equation (hBSE)[1] for two massive scalars interacting via the exchange of a massive scalar, a problem previously addressed with classical computation [2]. To achieve this, we transform the hBSE,by a suitable discretization, into a non-symmetric generalized eigenvalue problem (GEVP) (see Ref. [2]...
We simulate topological dissipative phases in a one-dimensional chain of trapped ions with their vibrational degrees of freedom. First, we study non-reciprocity in a two-ion parametric dimer and then we analyze topological amplification in large chains where Coulomb long-range couplings become apparent.
The existence of topologically non-trivial phases leads to the presence of edge states...
Fuel cells offer an elegant means of harnessing the chemical energy stored within the bonds of hydrogen and oxygen, converting it into electrical energy. However, existing fuel cell technologies suffer by a significant overpotential during the oxygen reduction reaction (ORR) at the cathode.
Given hydrogen's pivotal role as a promising low-carbon and sustainable fuel for the future, there is a...