title: Programmable multimode quantum networks.
abstract: Entanglement between large numbers of quantum modes is the quintessential resource for future technologies such as the quantum internet. Conventionally, the generation of multimode entanglement in optics requires complex layouts of beamsplitters and phase shifters in order to transform the input modes into entangled modes. Here we report the highly versatile and efficient generation of various multimode entangled states with the ability to switch between different linear optics networks in real time. By defining our modes to be combinations of different spatial regions of one beam, we may use just one pair of multi-pixel detectors in order to measure multiple entangled modes. We programme virtual networks that are fully equivalent to the physical linear optics networks they are emulating. We present results for N=2 up to N=8 entangled modes here, including N=2, 3, 4 cluster states. Our approach introduces the highly sought after attributes of flexibility and scalability to multimode entanglement.
authors.affiliation: Australian Centre for Quantum-Atom Optics, Department of Quantum Science, The Australian National University, Canberra, ACT 0200, Australia. seiji.armstrong@gmail.com
authors.forename: Seiji
authors.initials: S
authors.lastname: Armstrong
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Morizur
authors.forename: Jiri
authors.initials: J
authors.lastname: Janousek
authors.forename: Boris
authors.initials: B
authors.lastname: Hage
authors.forename: Nicolas
authors.initials: N
authors.lastname: Treps
authors.forename: Ping Koy
authors.initials: PK
authors.lastname: Lam
authors.forename: Hans-A
authors.initials: HA
authors.lastname: Bachor