The concept of squeezing and uncertainty relations are discussed for multimode quantum light with the consideration of polarization. Using the polarization gauge SU(2) invariance of free electromagnetic fields, we separate the polarization and biphoton degrees of freedom from other ones, and consider uncertainty relations characterizing polarization and biphoton observables. As a consequence, we obtain a new classification of states of unpolarized (and partially polarized) light within quantum optics. We also discuss briefly some interrelations of our analysis with experiments connected with solving some fundamental problems of physics.The concept of squeezing and uncertainty relations are discussed for multimode quantum light with the consideration of polarization. Using the polarization gauge SU(2) invariance of free electromagnetic fields, we separate the polarization and biphoton degrees of freedom from other ones, and consider uncertainty relations characterizing polarization and biphoton observables. As a consequence, we obtain a new classification of states of unpolarized (and partially polarized) light within quantum optics. We also discuss briefly some interrelations of our analysis with experiments connected with solving some fundamental problems of physics.

May 1, 19940 citations

Polarization structure of quantum light fields: a new insight. I. General outlook

V. P. Karassiov

A new consequent description of the polarization structure of light within the framework of quantum optics is given by using the polarization gauge SU(2) invariance of free electromagnetic fields and a related concept of the polarization (P) spin. Within this approach the quantum light may be thought as a mixture of the usual polarized photons and unpolarized biphotons. New classes of unpolarized light states generated by P-scalar biphotons are examined. Possible applications are briefly discussed.A new consequent description of the polarization structure of light within the framework of quantum optics is given by using the polarization gauge SU(2) invariance of free electromagnetic fields and a related concept of the polarization (P) spin. Within this approach the quantum light may be thought as a mixture of the usual polarized photons and unpolarized biphotons. New classes of unpolarized light states generated by P-scalar biphotons are examined. Possible applications are briefly discussed.

Journal of Physics A Mathematical and GeneralSep 7, 199363 citations

Quantum optics and squeezed states of light

Carlton M. Caves

uclaDec 1, 19880 citations

Development of Biphoton Entangled Light Spectroscopy (BELS) using Bell pairs

V. V. Desai, N. P. Armitage

We introduce Biphoton Entanglement Light Spectroscopy (BELS), a quantum spectroscopic technique that employs polarization entangled Bell pairs and two photon interference to probe material properties. In BELS, the measured signal arises not from single photon intensities but from changes in the joint polarization and path correlations of biphoton Bell pairs transmitted through or scattered by a sample and analyzed via cross channel coincidences. A key concept of BELS is the explicit mapping between Jones matrix operations and transformations within the Bell state manifold. Optical elements that are equivalent under classical polarization optics can produce qualitatively distinct signatures in the coincidence landscape when interrogated with entangled photons. We demonstrate that linear birefringence and Faraday rotation generate orthogonal admixtures of Bell states, yielding experimentally distinguishable coincidence channels within a single measurement. We measure birefringence in an anisotropic dielectric and Faraday rotation in $\text{Tb}_3\text{Ga}_5\text{O}_{12}$ . By mapping the changes to the photonic entanglement, BELS establishes a new framework for future entanglement enhanced spectroscopy, a potentially powerful approach in characterizing quantum materials, nanophotonic devices, and light matter interactions perhaps eventually at a fundamentally quantum level.We introduce Biphoton Entanglement Light Spectroscopy (BELS), a quantum spectroscopic technique that employs polarization entangled Bell pairs and two photon interference to probe material properties. In BELS, the measured signal arises not from single photon intensities but from changes in the joint polarization and path correlations of biphoton Bell pairs transmitted through or scattered by a sample and analyzed via cross channel coincidences. A key concept of BELS is the explicit mapping between Jones matrix operations and transformations within the Bell state manifold. Optical elements that are equivalent under classical polarization optics can produce qualitatively distinct signatures in the coincidence landscape when interrogated with entangled photons. We demonstrate that linear birefringence and Faraday rotation generate orthogonal admixtures of Bell states, yielding experimentally distinguishable coincidence channels within a single measurement. We measure birefringence in an anisotropic dielectric and Faraday rotation in $\text{Tb}_3\text{Ga}_5\text{O}_{12}$. By mapping the changes to the photonic entanglement, BELS establishes a new framework for future entanglement enhanced spectroscopy, a potentially powerful approach in characterizing quantum materials, nanophotonic devices, and light matter interactions perhaps eventually at a fundamentally quantum level.

quant-pharXiv:2603.22547Scientific ReportsMar 25, 20260 citations

\text{Tb}_3\text{Ga}_5\text{O}_{12}

. By mapping the changes to the photonic entanglement, BELS establishes a new framework for future entanglement enhanced spectroscopy, a potentially powerful approach in characterizing quantum materials, nanophotonic devices, and light matter interactions perhaps eventually at a fundamentally quantum level.