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Bell state analysis using orbital angular momentum and path degrees of freedom

Zi-Long Yang, Shi-Wen He, Lin-Cheng Wang, Si-Tong Jin, Liu Lv, Xiao-Ming Xiu, Chong Li

Abstract

Bell state analysis (BSA) constitutes a foundational operation for distinguishing Bell states in numerous quantum information processing (QIP) protocols. In this work, we propose a theoretical scheme for realizing a perfect BSA tailored for polarized Bell states, with assistance from orbital angular momentum (OAM) and path entanglement. The linear-optics-based architecture for BSA circumvents the inherent limitations of nonlinear optical processes and enhances the robustness against environmental noise -- a major challenge in practical QIP implementations. The integrating hyperentanglement (combining polarization, OAM, and path degrees of freedom (DOFs)) raises the theoretical success probability to 100%, achieving deterministic BSA. This deterministic BSA scheme offers a promising route toward practical, high-performance QIP in photonic systems, leveraging current experimental techniques and addressing key limitations of existing methods.

Bell state analysis using orbital angular momentum and path degrees of freedom

Abstract

Bell state analysis (BSA) constitutes a foundational operation for distinguishing Bell states in numerous quantum information processing (QIP) protocols. In this work, we propose a theoretical scheme for realizing a perfect BSA tailored for polarized Bell states, with assistance from orbital angular momentum (OAM) and path entanglement. The linear-optics-based architecture for BSA circumvents the inherent limitations of nonlinear optical processes and enhances the robustness against environmental noise -- a major challenge in practical QIP implementations. The integrating hyperentanglement (combining polarization, OAM, and path degrees of freedom (DOFs)) raises the theoretical success probability to 100%, achieving deterministic BSA. This deterministic BSA scheme offers a promising route toward practical, high-performance QIP in photonic systems, leveraging current experimental techniques and addressing key limitations of existing methods.

Paper Structure

This paper contains 8 sections, 20 equations, 2 figures, 2 tables.

Table of Contents

  1. INTRODUCTION
  2. Manipulation of states
  3. Polarization-controlled OAM shift gate
  4. OAM-controlled path shift gate
  5. OAM Hadamard gate
  6. Single-photon projective measurement
  7. Schematic design
  8. Conclusion

Figures (2)

  • Figure 1: Schematic diagram of quantum logic gates implemented using linear optical elements. (a) The P-COS gate is used to introduce a topological charge $2q$ controlled by horizontal and vertical polarization states. (b) The O-CPS gate is used to sort incident photons into distinct path modes determined by the positive and negative OAM modes. M denotes a mirror whose operation $\left| l \right\rangle \to e^{i\pi/2}\left| -l \right\rangle$. (c) The SPPM is used to identify the output hyperentangled Bell states based on the clicks of different detectors.
  • Figure 2: Schematic diagram of the complete polarized BSA assisted by the auxiliary path and OAM DOFs. QWP denotes a quarter-wave plates oriented at an angle $-\pi/4$. QP denotes a q-plate with topological charges $q=1/2$. SPP$_{1}$ and SPP$_{2}$ denote spiral phase plates with OAM quantum numbers ${+1}$ and ${-1}$, respectively. DP$_{1}$ and DP$_{2}$ denote dove prisms oriented at angles $-\pi/4$ and $0$, respectively. DL is the delay line. HWP denotes a half-wave plate rotated at an angle ${{\pi\mathord{\left/{\newline} \right.\nulldelimiterspace} 8}}$.