94 citations · 273 across the 17 of their papers we have counts for
18 papers
Witnessing quantum non-Gaussianity from intensity moments
Éva Rácz, László Ruppert, Radim Filip
Direct measurement of quantum non-Gaussianity requires some variant of a discrete photon-resolving detection, which is feasible only for low mean photon numbers. For a large mean p…
Certifying non-classicality and non-Gaussianity through optical parametric amplification
Mahmoud Kalash, Marcello H. M. Passos, Éva Rácz +3
Non-Gaussian states of light are essential for numerous quantum information protocols; thus, certifying non-Gaussianity is crucial. Full quantum state tomography, commonly used for…
Efficient OPA tomography of non-Gaussian states of light
Éva Rácz, László Ruppert, Radim Filip
Current advances in nonlinear optics have made it possible to perform a homodyne-like tomography of an unknown state without highly efficient detectors or a strong local oscillator…
Quantifying optical rogue waves
Eva Rácz, Kirill Spasibko, Mathieu Manceau +3
This work presents two distinct approaches to estimating the exponent related to the distribution of optical rogue waves observed in supercontinuum generated in a single-mode fiber…
Force sensing in an optomechanical system with feedback-controlled in-loop light
F. Bemani, O. Černotík, L. Ruppert +2
Quantum control techniques applied at macroscopic scales provide us with opportunities in fundamental physics and practical applications. Among them, measurement-based feedback all…
Estimation of heavy tails in optical non-linear processes
Éva Rácz, László Ruppert, Radim Filip
In optical non-linear processes rogue waves can be observed, which can be mathematically described by heavy-tailed distributions. These distributions are special due to the fact th…
Fading channel estimation for free-space continuous-variable secure quantum communication
László Ruppert, Christian Peuntinger, Bettina Heim +6
We investigate estimation of fluctuating channels and its effect on security of continuous-variable quantum key distribution. We propose a novel estimation scheme which is based on…
Light-matter quantum interferometry with homodyne detection
László Ruppert, Radim Filip
We investigated the estimation of an unknown Gaussian process (containing displacement, squeezing and phase-shift) applied to a matter system. The state of the matter system is not…
Estimation of nonclassical independent Gaussian processes by classical interferometry
László Ruppert, Radim Filip
We propose classical interferometry with low-intensity thermal radiation for the estimation of nonclassical independent Gaussian processes in material samples. We generally determi…
Quantum communication with macroscopically bright nonclassical states
Vladyslav C. Usenko, Laszlo Ruppert, Radim Filip
We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne…
Optimal quantum-state tomography with known parameters
Dénes Petz, László Ruppert
It is a well-known fact that the optimal POVM for quantum state tomography is the symmetric, informationally complete, positive operator valued measure (SIC-POVM). We investigate t…
Optimal parameter estimation of Pauli channels
László Ruppert, Dániel Virosztek, Katalin Hangos
The optimal measurement configuration, i.e., the optimal input quantum state and measurement in the form of a POVM with two elements, is investigated in this paper for qubit and ge…
Estimation of covariance matrix of macroscopic quantum states
László Ruppert, Vladyslav C. Usenko, Radim Filip
For systems analogous to a linear harmonic oscillator, the simplest way to characterize the state is by a covariance matrix containing the symmetrically-ordered moments of operator…
Entanglement-based continuous-variable quantum key distribution with multimode states and detectors
Vladyslav C. Usenko, Laszlo Ruppert, Radim Filip
Secure quantum key distribution with multimode Gaussian entangled states and multimode homodyne detectors is proposed. In general the multimode character of both the sources of ent…
Long-distance continuous-variable quantum key distribution with efficient channel estimation
László Ruppert, Vladyslav C. Usenko, Radim Filip
We investigate the main limitations which prevent the continuous-variable quantum key distribution protocols from achieving long distances in the finite-size setting. We propose a…
Pauli channel tomography with unknown channel directions
Dániel Virosztek, László Ruppert, Katalin M. Hangos
In this paper we estimate the parameters of the qubit Pauli channel using the channel matrix formalism. The main novelty of this work is that we do not assume the directions of the…
Conditional SIC-POVMs
D. Petz, L. Ruppert, A. Szanto
In this paper we examine a generalization of the symmetric informationally complete POVMs. SIC-POVMs are the optimal measurements for full quantum tomography, but if some parameter…
Efficient quantum tomography needs complementary and symmetric measurements
Denes Petz, Laszlo Ruppert
In this study the determinant of the average quadratic error matrix is used as the measure of state estimation efficiency. This quantity is easily computable in some cases, so it g…