Intrinsic upper bound on two-qubit polarization entanglement predetermined by pump polarization correlations in parametric down-conversion

Abstract

We study how one-particle correlations transfer to manifest as two-particle correlations in the context of parametric down-conversion (PDC), a process in which a pump photon is annihilated to produce two entangled photons. We work in the polarization degree of freedom and show that for any two-qubit generation process that is both trace-preserving and entropy-nondecreasing, the concurrence $C(\rho )$ of the generated two-qubit state $\rho$ follows an intrinsic upper bound with $C(\rho )\le (1+P)/2$, where $P$ is the degree of polarization of the pump photon. We also find that for the class of two qubit states that is restricted to have only two non-zero diagonal elements such that the effective dimensionality of the two-qubit state is same as the dimensionality of the pump polarization state, the upper bound on concurrence is the degree of polarization itself, that is, $C(\rho )\le P$. Our work shows that the maximum manifestation of two-particle correlations as entanglement is dictated by one-particle correlations. The formalism developed in this work can be extended to include multi-particle systems and can thus have important implications towards deducing the upper bounds on multi-particle entanglement, for which no universally accepted measure exists.

5 pages, 2 figures

References in corpus (9)

• Free-Space distribution of entanglement and single photons over 144 km
• Measuring Quantum Coherence with Entanglement
• Observable measure of quantum coherence in finite dimensional systems
• Quantum coherence in multipartite systems
• Direct generation of three-photon polarization entanglement
• Revealing Hidden Coherence in Partially Coherent Light
• Temporal Coherence and Indistinguishability in Two-Photon Interference Effects
• Entanglement transfer from electron spins to photons in spin light-emitting diodes containing quantum dots
• Transfer of entanglement from electrons to photons by optical selection rules

Cited by in corpus (8)

• Transfer of temporal coherence in parametric down-conversion
• Experimental generation of polarization entanglement from spontaneous parametric down-conversion pumped by spatiotemporally highly incoherent light
• Postselection-free controlled generation of a high-dimensional orbital-angular-momentum entangled state
• Intrinsic degree of coherence of two-qubit states and measures of two-particle quantum correlations
• Dependence of the photon statistics of down-converted field-modes on the photon statistics of pump field-mode
• Quantum entropy and polarization measurements of the two-photon system
• Violation of local realism with spatially multimode parametric down-conversion pumped by spatially incoherent light
• Spectrally Resolved Higher Order Photon Statistics of Spontaneous Parametric Down Conversion