Absolute Quantum Efficiency Measurements by Means of Conditioned Polarization Rotation

Ultrahigh Precision Absolute and Relative Rotation Sensing using Fast and Slow Light

We describe a resonator based optical gyroscope whose sensitivity for measuring absolute rotation is enhanced via use of the anomalous dispersion characteristic of superluminal light propagation. The enhancement is given by the inverse of the group index, saturating to a bound determined by the group velocity dispersion. We also show how the offsetting effect of the concomitant broadening of the resonator linewidth may be circumvented by using an active cavity. For realistic conditions, the enhancement factor is as high as 106. We also show how normal dispersion used for slow light can enhance…

Conditioned Unitary Transformation on biphotons

A conditioned unitary transformation ($90^o$ polarization rotation) is performed at single-photon level. The transformation is realized by rotating polarization for one of the photons of a polarization-entangled biphoton state (signal photon) by means of a Pockel's cell triggered by the detection of the other (idler) photon after polarization selection. As a result, polarization degree for the signal beam changes from zero to the value given by the idler detector quantum efficiency. This result is relevant to practical realization of various quantum information schemes and can be used for deve…

Rotational Properties and GHZ Contradictions in N-Qubit Systems

Rotational symmetries of N-qubit Greenberger-Horne-Zeilinger (GHZ) states directly exhibit their nonlocality and render transparent the many possible measurements that produce absolute contradictions with local realism. While N measurements fix the assumed elements of reality, an exponentially growing number of absolute contradictions occurs. Operators that represent the detector settings provide a faithful representation of the symmetry group, and demonstrate Kochen-Specker contextuality.

数字闭环热原子束干涉仪的理论提案：用于高带宽、宽动态范围和同时绝对加速度-旋转传感

Theoretical Proposal of a Digital Closed-Loop Thermal Atomic-Beam Interferometer for High-Bandwidth, Wide-Dynamic-Range, and Simultaneous Absolute Acceleration-Rotation Sensing

该研究提出一种数字闭环热原子束干涉仪，用于高带宽、宽动态范围的绝对加速度和旋转同时测量，展现出优于现有惯性导航系统传感器的性能。

In-Situ absolute phase detection of a microwave field via incoherent fluorescence

Measuring the amplitude and the absolute phase of a monochromatic microwave field at a specific point of space and time has many potential applications, including precise qubit rotations and wavelength quantum teleportation. Here we show how such a measurement can indeed be made using resonant atomic probes, via detection of incoherent fluorescence induced by a laser beam. This measurement is possible due to self-interference effects between the positive and negative frequency components of the field. In effect, the small cluster of atoms here act as a highly localized pick-up coil, and the fl…

Twin-photon techniques for photo-detector calibration

The aim of this review paper is to enlighten some recent progresses in quantum optical metrology in the part of quantum efficiency measurements of photo-detectors performed with bi-photon states. The intrinsic correlated nature of entangled photons from Spontaneous Parametric Down Conversion phenomenon has opened wide horizons to a new approach for the absolute measurement of photo-detector quantum efficiency, outgoing the requirement for conventional standards of optical radiation; in particular the simultaneous feature of the creation of conjugated photons led to a well known technique of co…