Schrödinger cat states in continuous variable non-Gaussian networks

• Published in: Physics letters. A 2020-10, Vol.384 (29), p.126762, Article 126762
• Main Author: Sokolov, I.V.
• Format: Article
• Language: English
• Subjects: Continuous variable quantum networks; Measurement-induced evolution; Non-Gaussian gates; Schrödinger cat states
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/j.physleta.2020.126762

•Continuous variable network with non-Gaussian gate prepares Schrodinger cat state.•Lowest order non-Gaussian resource: a cubic phase state is sufficient.•Superposition of two copies of an arbitrary input state can be created.•Intuitively clear interpretation of cat state emergence is presented.•Heisenberg picture as it is applied to Gaussian networks fails for “cat gate”. We show how continuous variable network with embedded non-Gaussian element can effectively prepare Schrödinger cat state using cubic phase state as elementary non-Gaussian resource, an entangling Gaussian gate, and homodyne measurement. The gate prepares superposition of two “copies” of an arbitrary input state well separated on the phase plane. A key feature of the cat-breeding configuration is that the measurement outcome provides multivalued information about the target system variables, which makes irrelevant the Heisenberg picture as it is applied to Gaussian networks. We present an intuitively clear interpretation of the emerging cat state, extendable to the circuits with other non-Gaussian elements.