Manipulation of continuous variable orbital angular momentum squeezing and entanglement by pump shaping.

Area of Science:

• Quantum Optics
• Quantum Information Science
• Nonlinear Optics

Background:

• Spatially structured quantum states, including orbital angular momentum (OAM) squeezing and entanglement, are crucial in quantum optics.
• Efficient methods for generating and manipulating these spatial quantum states on demand are essential for advancing quantum technologies.

Purpose of the Study:

• To explore novel methods for generating and manipulating spatial quantum states, specifically OAM squeezed and entangled states.
• To demonstrate the direct generation of OAM mode squeezed states using an optical parametric oscillator (OPO).

Main Methods:

• Directly generated OAM mode squeezed states for LG0+1 and LG0-1 modes using an OPO.
• Manipulated the nonlinear process within the OPO by controlling the relative phase of two different spatial multimode pump beams.
• Characterized Laguerre-Gaussian (LG) entangled states by indirectly measuring squeezing and directly measuring entanglement between specific OAM modes.

Main Results:

• Achieved OAM mode squeezing of -5.4 dB for the LG0+1 mode and -5.3 dB for the LG0-1 mode.
• Successfully generated OAM mode squeezed and entangled states by controlling the OPO's nonlinear dynamics.
• Demonstrated effective characterization of entangled states involving specific HG and LG modes.

Conclusions:

• The study presents the first direct generation of OAM squeezed states using an OPO.
• Effective manipulation of OAM quantum states was achieved by controlling the nonlinear optical processes.
• This work provides new insights into on-demand continuous variable quantum state generation for high-dimensional quantum information and metrology.