Quantum switch for single-photon transport in a coupled superconducting transmission-line-resonator array

Abstract

We propose and study an approach to realize quantum switch for single-photon transport in a coupled superconducting transmission-line-resonator ͑TLR͒ array with one controllable hopping interaction. We find that the single photon with arbitrary wave vector can transport in a controllable way in this system. We also study how to realize controllable hopping interaction between two TLRs via a Cooper-pair box ͑CPB͒. When the frequency of the CPB is largely detuned from those of the two TLRs, the variables of the CPB can be adiabatically eliminated and thus a controllable interaction between two TLRs can be obtained.Coupled cavity arrays ͑CCAs͒ ͓1͔ have recently attracted considerable attentions of both theorists and experimentalists. The CCAs have been proposed to implement quantum simulators for many-body physics, such as discovering new matter phases of photons ͓2-4͔ and providing a new platform to study spin systems ͓5,6͔. The CCAs are also suggested to manipulate photons for optical quantum information processing ͓7-9͔. Moreover, photon transport in the CCAs has been investigated ͓10-14͔. There are several possible ways to construct the CCAs, for example: ͑i͒ coupled defect cavities in photonic crystals ͓15͔; ͑ii͒ coupled toroidal microresonators ͓16͔; and ͑iii͒ coupled superconducting transmission-line resonators ͑TLRs͒ ͓11,12͔.In CCAs, there have been many proposals to realize quantum switch ͓17,18͔, which is used to control single-photon transport ͓11,19-21͔. For example, the reflection and transmission of photons in a coupled resonator waveguide can be controlled by a tunable two-level quantum system ͓11,18͔, acting as a controller.Here, we study another approach to control the singlephoton transport in a CCA, which consists of a chain of TLRs ͓22,23͔. In our proposal, the controllable transport is realized by a tunable coupling. As we know, how to control coupling between two solid devices is a major challenge in scalable quantum computing circuits ͓24-30͔. To obtain a tunable coupling, we propose that a Cooper-pair box ͑CPB͒ acts as a coupler. When the frequency of the coupler is largely detuned from those of the two resonators, the variables of the coupler can be adiabatically eliminated and thus a controllable interaction can be induced. Compared with previous approach ͓11͔, this approach has following advantage: dynamical variables of the coupler are adiabatically eliminated, therefore the coupler is a passive controlling element, which makes robust to prevent from the environment of the coupler.As shown in Fig. 1, one-dimensional CCA is a chain of N cavities, each is only coupled to its nearest-neighbor ones, Figs. 1͑a͒ and 1͑b͒ are the site lattice model and the schematic of coupled TLR array, respectively. The TLRs are assumed to have the same frequency. We also assume that the coupling strength between two nearest-neighbor TLRs is the same, except one between the lth and ͑l +1͒th TLRs. The Hamiltonian of the system is H = ͚ n a n † a n − t ͚ n ͑a n † a n+1 + a n+1 † a n ͒ − t͑a l † a l+1 + a l+1 † a...

Scattering of two distinguishable photons by aΞ-type three-level atom in a one-dimensional waveguide

“…The transport properties of single photons controlled by interaction with atoms (or artificial atoms) inside a onedimensional waveguide have been a subject of considerable interest in recent years [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In waveguide quantum electrodynamics (QED) systems, atoms can strongly interact with a continuum of field modes compared with those in free space, and the propagation directions of photons can be well monitored.…”

Waveguide quantum electrodynamics: Controllable channel from quantum interference

“…Gy, 42.50.Ct, 03.65.Nk In a fully-quantum network based on single photon carriers to process quantum information, the essential task is to coherently control photon propagation by a local quantum node [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. To this end, a hybrid system consisting of a one-dimensional (1D) waveguide coupled to a two-level system (TLS) is extensively studied for physical implementation of the quantum node acting as a quantum switch [4][5][6][7][8][9][10][11][12] or a single photon transistor [13,14]. With the single mode approximation for a waveguide with infinitesimal cross section, the total reflection of single photons by the TLS was found to be responsible for the dominant functions of quantum devices.…”

Effective gauge potentials induced by superconducting quantum circuits

“…1, an operated CPB circuit is connected via capacitances C k to two high-Q coplanar TLRs with the respective single-mode frequency ω k [25,26], k = 1 and 2, the identical geometric lengths of the one-dimensional TLRs are L r . The considered CPB consists of a superconducting island with extra Cooper-pairs n, the island is coupled by two symmetric Josephson junctions (each with coupling energy E J 0 and capacitance C J ) to a segment of a superconducting ring.…”

“…With the currently attainable parameters[5,26], C 2 = 6 fF, C t = 1.6 pF, L r = 24 mm, the coupling strength λ (a) 12 between |s 1 and |s 2 caused by the chosen cavity mode ω 2 /2π (= 7.95 GHz) reaches an order of ∼ 0.29E c (= 1.45 GHz), which satisfies the dispersive condition, and then the cavity mode can hardly induce the transition between |s 2 and |s 1 . As a result, the quantum leakages are negligible in the operated three-level system.…”