More Like this

1. Continuous-variable quantum computing in the quantum optical frequency comb

   https://doi.org/10.1088/1361-6455/ab526f  

   Pfister, Olivier ( November 2019 , Journal of Physics B: Atomic, Molecular and Optical Physics)

   This topical review introduces the theoretical and experimental advances in continuous-variable (CV)—i.e. qumode-based in lieu of qubit-based—large-scale, fault-tolerant quantum computing and quantum simulation. An introduction to the physics and mathematics of multipartite entangled CV cluster states is given, and their connection to experimental concepts is delineated. Paths toward fault tolerance are also presented. It is the hope of the author that this review attract more contributors to the field and promote its extension to the promising technology of integrated quantum photonics.

    

   more » « less
2. Quantum repeaters based on concatenated bosonic and discrete-variable quantum codes

   https://doi.org/10.1038/s41534-021-00438-7  

   Rozpędek, Filip ; Noh, Kyungjoo ; Xu, Qian ; Guha, Saikat ; Jiang, Liang ( June 2021 , npj Quantum Information)

   We propose an architecture of quantum-error-correction-based quantum repeaters that combines techniques used in discrete- and continuous-variable quantum information. Specifically, we propose to encode the transmitted qubits in a concatenated code consisting of two levels. On the first level we use a continuous-variable GKP code encoding the qubit in a single bosonic mode. On the second level we use a small discrete-variable code. Such an architecture has two important features. Firstly, errors on each of the two levels are corrected in repeaters of two different types. This enables for achieving performance needed in practical scenarios with a reduced cost with respect to an architecture for which all repeaters are the same. Secondly, the use of continuous-variable GKP code on the lower level generates additional analog information which enhances the error-correcting capabilities of the second-level code such that long-distance communication becomes possible with encodings consisting of only four or seven optical modes.

    

   more » « less
3. A squeezed quantum microcomb on a chip

   https://doi.org/10.1038/s41467-021-25054-z  

   Yang, Zijiao ; Jahanbozorgi, Mandana ; Jeong, Dongin ; Sun, Shuman ; Pfister, Olivier ; Lee, Hansuek ; Yi, Xu ( August 2021 , Nature Communications)

   The optical microresonator-based frequency comb (microcomb) provides a versatile platform for nonlinear physics studies and has wide applications ranging from metrology to spectroscopy. The deterministic quantum regime is an unexplored aspect of microcombs, in which unconditional entanglements among hundreds of equidistant frequency modes can serve as critical ingredients to scalable universal quantum computing and quantum networking. Here, we demonstrate a deterministic quantum microcomb in a silica microresonator on a silicon chip. 40 continuous-variable quantum modes, in the form of 20 simultaneously two-mode squeezed comb pairs, are observed within 1 THz optical span at telecommunication wavelengths. A maximum raw squeezing of 1.6 dB is attained. A high-resolution spectroscopy measurement is developed to characterize the frequency equidistance of quantum microcombs. Our demonstration offers the possibility to leverage deterministically generated, frequency multiplexed quantum states and integrated photonics to open up new avenues in fields of spectroscopy, quantum metrology, and scalable, continuous-variable-based quantum information processing.

    

   more » « less
4. Measurement-based generation and preservation of cat and grid states within a continuous-variable cluster state

   https://doi.org/10.22331/q-2022-07-20-769  

   Eaton, Miller ; González-Arciniegas, Carlos ; Alexander, Rafael N. ; Menicucci, Nicolas C. ; Pfister, Olivier ( July 2022 , Quantum)

   We present an algorithm to reliably generate various quantum states critical to quantum error correction and universal continuous-variable (CV) quantum computing, such as Schrödinger cat states and Gottesman-Kitaev-Preskill (GKP) grid states, out of Gaussian CV cluster states. Our algorithm is based on the Photon-counting-Assisted Node-Teleportation Method (PhANTM), which uses standard Gaussian information processing on the cluster state with the only addition of local photon-number-resolving measurements. We show that PhANTM can apply polynomial gates and embed cat states within the cluster. This method stabilizes cat states against Gaussian noise and perpetuates non-Gaussianity within the cluster. We show that existing protocols for breeding cat states can be embedded into cluster state processing using PhANTM. 

   more » « less
5. Topological optical parametric oscillation

   https://doi.org/10.1515/nanoph-2021-0765  

   Roy, Arkadev ; Parto, Midya ; Nehra, Rajveer ; Leefmans, Christian ; Marandi, Alireza ( February 2022 , Nanophotonics)

   Abstract Topological insulators possess protected boundary states which are robust against disorders and have immense implications in both fermionic and bosonic systems. Harnessing these topological effects in nonequilibrium scenarios is highly desirable and has led to the development of topological lasers. The topologically protected boundary states usually lie within the bulk bandgap, and selectively exciting them without inducing instability in the bulk modes of bosonic systems is challenging. Here, we consider topological parametrically driven nonlinear resonator arrays that possess complex eigenvalues only in the edge modes in spite of the uniform pumping. We show parametric oscillation occurs in the topological boundary modes of one and two dimensional systems as well as in the corner modes of a higher order topological insulator system. Furthermore, we demonstrate squeezing dynamics below the oscillation threshold, where the quantum properties of the topological edge modes are robust against certain disorders. Our work sheds light on the dynamics of weakly nonlinear topological systems driven out-of-equilibrium and reveals their intriguing behavior in the quantum regime. 

   more » « less