The emerging strategy to overcome the limitations of bulk quantum optics experiments consists of taking advantage of the robustness and compactness of the integrated waveguide technology. Indeed, high-quality quantum photonic circuits can be conveniently realized by femtosecond laser waveguide writing, exploiting the unique features of this fabrication technique.
The high processing speed enables to produce with low cost and rapid turnaround many different circuit designs, easing the experimental testing of new ideas. The unique three-dimensional capabilities empower the design of devices and circuit configurations with novel functionalities and enhanced compactness. In addition, the low birefringence of femtosecond laser written waveguides makes them suitable for propagating qubits encoded in the polarization degree of freedom.
Several applications have been addressed up to now, in the fields of quantum computing, quantum simulation and quantum metrology. An integrated CNOT logic gate has been realized. Circuits integrating tens of optical components in a single chip, injected with entangled two-photon states, have enabled to simulate the dynamics of bosonic or fermionic pairs of particles undergoing quantum walks. An optofluidic chip for quantum biosensing has been demonstrated.
Collaborations: F. Sciarrino and P. Mataloni (La Sapienza Università), M. Lobino and J. O'Brien (Bristol University)