title: Integrated photonic quantum gates for polarization qubits.
abstract: The ability to manipulate quantum states of light by integrated devices may open new perspectives both for fundamental tests of quantum mechanics and for novel technological applications. However, the technology for handling polarization-encoded qubits, the most commonly adopted approach, is still missing in quantum optical circuits. Here we demonstrate the first integrated photonic controlled-NOT (CNOT) gate for polarization-encoded qubits. This result has been enabled by the integration, based on femtosecond laser waveguide writing, of partially polarizing beam splitters on a glass chip. We characterize the logical truth table of the quantum gate demonstrating its high fidelity to the expected one. In addition, we show the ability of this gate to transform separable states into entangled ones and vice versa. Finally, the full accessibility of our device is exploited to carry out a complete characterization of the CNOT gate through a quantum process tomography.
authors: Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci, 32, I-20133 Milano, Italy.
authors: Andrea
authors: A
authors: Crespi
authors: Roberta
authors: R
authors: Ramponi
authors: Roberto
authors: R
authors: Osellame
authors: Linda
authors: L
authors: Sansoni
authors: Irene
authors: I
authors: Bongioanni
authors: Fabio
authors: F
authors: Sciarrino
authors: Giuseppe
authors: G
authors: Vallone
authors: Paolo
authors: P
authors: Mataloni