TY  - JOUR
AU  - Trényi, Róbert
AU  - Lukács, Árpád László
AU  - Horodecki, Paweł
AU  - Horodecki, Ryszard
AU  - Vértesi, Tamás
AU  - Tóth, Géza
TI  - Activation of metrologically useful genuine multipartite entanglement
JF  - NEW JOURNAL OF PHYSICS
J2  - NEW J PHYS
VL  - 26
PY  - 2024
IS  - 2
PG  - 18
SN  - 1367-2630
DO  - 10.1088/1367-2630/ad1e93
UR  - https://m2.mtmt.hu/api/publication/34598185
ID  - 34598185
N1  - Export Date: 07 March 2024
AB  - We consider quantum metrology with several copies of bipartite and multipartite quantum states. We characterize the metrological usefulness by determining how much the state outperforms separable states. We identify a large class of entangled states that become maximally useful for metrology in the limit of large number of copies, even if the state is weakly entangled and not even more useful than separable states. This way we activate metrologically useful genuine multipartite entanglement. Remarkably, not only that the maximally achievable metrological usefulness is attained exponentially fast in the number of copies, but it can be achieved by the measurement of few simple correlation observables. We also make general statements about the usefulness of a single copy of pure entangled states. We surprisingly find that the multiqubit states presented in Hyllus et al (2010 Phys. Rev. A 82 012337), which are not useful, become useful if we embed the qubits locally in qutrits. We discuss the relation of our scheme to error correction, and its possible use for quantum metrology in a noisy environment.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Tóth, Géza
AU  - Pitrik, József
TI  - Quantum Wasserstein distance based on an optimization over separable states
JF  - QUANTUM
J2  - QUANTUM-AUSTRIA
VL  - 7
PY  - 2023
PG  - 25
SN  - 2521-327X
DO  - 10.22331/q-2023-10-16-1143
UR  - https://m2.mtmt.hu/api/publication/34308959
ID  - 34308959
AB  - We define the quantum Wasserstein distance such that the optimization of the coupling is carried out over bipartite separable states rather than bipartite quantum states in general, and examine its properties. Sur-prisingly, we find that the self-distance is related to the quantum Fisher information. We present a transport map corresponding to an optimal bipartite separable state. We discuss how the quantum Wasserstein distance introduced is connected to criteria detecting quantum entanglement. We define variance -like quantities that can be obtained from the quantum Wasserstein distance by replacing the minimization over quantum states by a maximization. We extend our results to a family of generalized quantum Fisher infor-mation quantities.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Vitagliano, G
AU  - Fadel, M
AU  - Apellaniz, I
AU  - Kleinmann, M
AU  - Lucke, B
AU  - Klempt, C
AU  - Tóth, Géza
TI  - Number-phase uncertainty relations and bipartite entanglement detection in spin ensembles
JF  - QUANTUM
J2  - QUANTUM-AUSTRIA
VL  - 7
PY  - 2023
PG  - 34
SN  - 2521-327X
DO  - 10.22331/q-2023-02-09-914
UR  - https://m2.mtmt.hu/api/publication/33935430
ID  - 33935430
N1  - Export Date: 08 March 2024
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Tóth, Géza
AU  - Fröwis, F.
TI  - Uncertainty relations with the variance and the quantum Fisher information based on convex decompositions of density matrices
JF  - PHYSICAL REVIEW RESEARCH
J2  - PRRESEARCH
VL  - 4
PY  - 2022
IS  - 1
PG  - 16
SN  - 2643-1564
DO  - 10.1103/PhysRevResearch.4.013075
UR  - https://m2.mtmt.hu/api/publication/32836858
ID  - 32836858
N1  - Export Date: 27 March 2024
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Tóth, Géza
AU  - Vértesi, Tamás
AU  - Horodecki, P.
AU  - Horodecki, R.
TI  - Activating hidden metrological usefulness
JF  - OPTICS INFOBASE CONFERENCE PAPERS
J2  - OPTICS INFOBASE CONF PAP
VL  - 2021
PY  - 2021
SN  - 2162-2701
DO  - 10.1364/QIM.2021.Th2A.6
UR  - https://m2.mtmt.hu/api/publication/32849851
ID  - 32849851
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Pál, Károly Ferenc
AU  - Tóth, Géza
AU  - Bene, Erika
AU  - Vértesi, Tamás
TI  - Bound entangled singlet-like states for quantum metrology
JF  - PHYSICAL REVIEW RESEARCH
J2  - PRRESEARCH
VL  - 3
PY  - 2021
IS  - 2
PG  - 18
SN  - 2643-1564
DO  - 10.1103/PhysRevResearch.3.023101
UR  - https://m2.mtmt.hu/api/publication/32079102
ID  - 32079102
N1  - Export Date: 27 March 2024
LA  - English
DB  - MTMT
ER  - 

TY  - THES
AU  - Tóth, Géza
TI  - Entanglement detection and quantum metrology in quantum optical systems
PB  - MTA Wigner Fizikai Kutatóközpont
PY  - 2020
SP  - 95
UR  - https://m2.mtmt.hu/api/publication/33675605
ID  - 33675605
LA  - Hungarian
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Tóth, Géza
AU  - Vértesi, Tamás
AU  - Horodecki, P
AU  - Horodecki, R
TI  - Activating Hidden Metrological Usefulness
JF  - PHYSICAL REVIEW LETTERS
J2  - PHYS REV LETT
VL  - 125
PY  - 2020
IS  - 2
PG  - 7
SN  - 0031-9007
DO  - 10.1103/PhysRevLett.125.020402
UR  - https://m2.mtmt.hu/api/publication/31382293
ID  - 31382293
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Kong, J.
AU  - Jiménez-Martínez, R.
AU  - Troullinou, C.
AU  - Lucivero, V.G.
AU  - Tóth, Géza
AU  - Mitchell, M.W.
TI  - Measurement-induced, spatially-extended entanglement in a hot, strongly-interacting atomic system
JF  - NATURE COMMUNICATIONS
J2  - NAT COMMUN
VL  - 11
PY  - 2020
IS  - 1
PG  - 9
SN  - 2041-1723
DO  - 10.1038/s41467-020-15899-1
UR  - https://m2.mtmt.hu/api/publication/31326912
ID  - 31326912
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Tóth, Géza
TI  - Stretching the limits of multiparticle entanglement
JF  - QUANTUM
J2  - QUANTUM-AUSTRIA
VL  - 4
PY  - 2020
PG  - 30
SN  - 2521-327X
DO  - 10.22331/qv-2020-01-27-30
UR  - https://m2.mtmt.hu/api/publication/31183896
ID  - 31183896
LA  - English
DB  - MTMT
ER  -