Demonstration of a Single-Photon Router in the Microwave Regime

Abstract

We have embedded an artificial atom, a superconducting transmon qubit, in an open transmission line and investigated the strong scattering of incident microwave photons (∼6 GHz). When an input coherent state, with an average photon number N≪1 is on resonance with the artificial atom, we observe extinction of up to 99.6% in the forward propagating field. We use two-tone spectroscopy to study scattering from excited states and we observe electromagnetically induced transparency (EIT). We then use EIT to make a single-photon router, where we can control to what output port an incoming signal is delivered. The maximum on-off ratio is around 99% with a rise and fall time on the order of nanoseconds, consistent with theoretical expectations. The router can easily be extended to have multiple output ports and it can be viewed as a rudimentary quantum node, an important step towards building quantum information networks.

Optomechanical systems as single-photon routers

“…Other proposals on a photon switch are based on using a single atom in a strongly coupled waveguide array [6] and using strongly coupled atoms via surface plasmons on a nanowire [7]. There are also reports of single photon switch at telecom wavelengths using strong cross phase modulation [8] and in the microwave domain using a superconducting transmon qubit [9]. It is now known that the optomechanical systems exhibit an analog of EIT [10] which has been observed in several experiments [11].…”

Implementation of an Impedance-MatchedΛSystem by Dressed-State Engineering

“…Lx, 85.25.Cp, 42.50.Pq In one-dimensional optical setups, radiation from a quantum emitter is guided completely to specified onedimensional propagating modes. We can realize such setups in a variety of physical systems, such as optical cavity quantum electrodynamics (QED) systems using atoms or quantum dots [1][2][3] and circuit QED systems using superconducting qubits [4][5][6]. When we apply a field to excite the emitter through the one-dimensional mode in these setups, the incident field inevitably interferes with the field scattered by the emitter due to the low dimensionality [7].…”

From Josephson junction metamaterials to tunable pseudo-cavities

“…The building block of these studies is the scattering of photons through a qubit [9,10,11] or a Josephson junction (JJ) [12]. The reflection and transmission properties of these nonlinear scatterers have been probed in experiments with qubits [13,14,15] and SQUIDs [16]. More recently, arrangements of qubits or JJs have been suggested to tailor the propagation of light [17,18,19,20,12,21], conforming what is now called quantum metamaterials, the topic of this special issue.…”

“…More recently, arrangements of qubits or JJs have been suggested to tailor the propagation of light [17,18,19,20,12,21], conforming what is now called quantum metamaterials, the topic of this special issue. These are low loss devices, since the underlying medium for the photon is a superconductor at a very low temperature, but they introduce new physics: from engineering of bandgaps and dispersion relation as in classical wave propagation, to purely quantum effects such as electromagnetic induced transparency (EIT) [22,14] and other quantum phenomena.…”