TY  - JOUR
A1  - Puhlmann, Dirk
A1  - Henkel, Carsten
A1  - Heuer, Axel
A1  - Pieplow, Gregor
A1  - Menzel, Ralf
T1  - Characterization of a remote optical element with bi-photons
JF  - Physica scripta : an international journal for experimental and theoretical physics
N2  - We present a simple setup that exploits the interference of entangled photon pairs. 'Signal' photons are sent through a Mach–Zehnder-like interferometer, while 'idlers' are detected in a variable polarization state. Two-photon interference (in coincidence detection) is observed with very high contrast and for significant time delays between signal and idler detection events. This is explained by quantum erasure of the polarization tag and a delayed choice protocol involving a non-local virtual polarizer. The phase of the two-photon fringes is scanned by varying the path length in the signal beam or by rotating a birefringent crystal in the idler beam. We exploit this to characterize one beam splitter of the signal photon interferometer (reflection and transmission amplitudes including losses), using only information about coincidences and control parameters in the idler path. This is possible because our bi-photon state saturates the Greenberger–Yelin–Englert inequality between contrast and predictability.
KW  - quantum optics
KW  - quantum eraser
KW  - entanglement
KW  - bi-photons
Y1  - 2016
U6  - https://doi.org/10.1088/0031-8949/91/2/023006
SN  - 0031-8949
SN  - 1402-4896
VL  - 91
SP  - 113
EP  - 114
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Henkel, Carsten
T1  - Heat transfer and entanglement
BT  - non-equilibrium correlation spectra of two quantum oscillators
JF  - Annalen der Physik
N2  - The non-equilibrium state of two oscillators with a mutual interaction and coupled to separate heat baths is discussed. Bosonic baths are considered, and an exact spectral representation for the elements of the covariance matrix is provided analytically. A wide class of spectral densities for the relevant bath modes is allowed for. The validity of the fluctuation-dissipation relation is established for global equilibrium (both baths at the same temperature) in the stationary state. Spectral measures of entanglement are suggested by comparing to the equilibrium spectrum of zero-point fluctuations. No rotating-wave approximation is applied, and anomalous heat transport from cold to hot bath, as reported in earlier work, is demonstrated not to occur.
KW  - entanglement
KW  - heat transfer
KW  - non-equilibrium steady state
KW  - master
KW  - equation
KW  - quantum thermodynamics
Y1  - 2021
U6  - https://doi.org/10.1002/andp.202100089
SN  - 0003-3804
SN  - 1521-3889
VL  - 533
IS  - 10
PB  - Wiley-VCH
CY  - Weinheim
ER  -