No Arabic abstract
We report the observation of efficient and low-noise frequency conversion between two microwave modes, mediated by the motion of a mechanical resonator subjected to radiation pressure. We achieve coherent conversion of more than $10^{12}~mathrm{photons/s}$ with a $95mathrm{%}$ efficiency and a $14~mathrm{kHz}$ bandwidth. With less than $10^{-1}~mathrm{photons cdot s^{-1}cdot Hz^{-1}}$ of added noise, this optomechanical frequency converter is suitable for quantum state transduction. We show the ability to operate this converter as a tunable beam splitter, with direct applications for photon routing and communication through complex quantum networks.
Microelectromechanical systems and integrated photonics provide the basis for many reliable and compact circuit elements in modern communication systems. Electro-opto-mechanical devices are currently one of the leading approaches to realize ultra-sensitive, low-loss transducers for an emerging quantum information technology. Here we present an on-chip microwave frequency converter based on a planar aluminum on silicon nitride platform that is compatible with slot-mode coupled photonic crystal cavities. We show efficient frequency conversion between two propagating microwave modes mediated by the radiation pressure interaction with a metalized dielectric nanobeam oscillator. We achieve bidirectional coherent conversion with a total device efficiency of up to ~ 60 %, a dynamic range of $2times10^9$ photons/s and an instantaneous bandwidth of up to 1.7 kHz. A high fidelity quantum state transfer would be possible if the drive dependent output noise of currently $sim14$ photons$ cdot $s$^{-1} cdot $Hz$^{-1}$ is further reduced. Such a silicon nitride based transducer is in-situ reconfigurable and could be used for on-chip classical and quantum signal routing and filtering, both for microwave and hybrid microwave-optical applications.
Fiber optic communication is the backbone of our modern information society, offering high bandwidth, low loss, weight, size and cost, as well as an immunity to electromagnetic interference. Microwave photonics lends these advantages to electronic sensing and communication systems, but - unlike the field of nonlinear optics - electro-optic devices so far require classical modulation fields whose variance is dominated by electronic or thermal noise rather than quantum fluctuations. Here we present a cavity electro-optic transceiver operating in a millikelvin environment with a mode occupancy as low as 0.025 $pm$ 0.005 noise photons. Our system is based on a lithium niobate whispering gallery mode resonator, resonantly coupled to a superconducting microwave cavity via the Pockels effect. For the highest continuous wave pump power of 1.48 mW we demonstrate bidirectional single-sideband conversion of X band microwave to C band telecom light with a total (internal) efficiency of 0.03 % (0.7 %) and an added output conversion noise of 5.5 photons. The high bandwidth of 10.7 MHz combined with the observed very slow heating rate of 1.1 noise photons s$^{-1}$ puts quantum limited pulsed microwave-optics conversion within reach. The presented device is versatile and compatible with superconducting qubits, which might open the way for fast and deterministic entanglement distribution between microwave and optical fields, for optically mediated remote entanglement of superconducting qubits, and for new multiplexed cryogenic circuit control and readout strategies.
Using different configurations of applied strong driving and weak probe fields, we find that only a single three-level superconducting quantum circuit (SQC) is enough to realize amplification, attenuation and frequency conversion of microwave fields. Such a three-level SQC has to possess $Delta$-type cyclic transitions. Different from the parametric amplification (attenuation) and frequency conversion in nonlinear optical media, the real energy levels of the three-level SQC are involved in the energy exchange when these processes are completed. We quantitatively discuss the effects of amplification (attenuation) and the frequency conversion for different types of driving fields. The optimal points are obtained for achieving the maximum amplification (attenuation) and conversion efficiency. Our study provides a new method to amplify (attenuate) microwave, realize frequency conversion, and also lay a foundation for generating single or entangled microwave photon states using a single three-level SQC.
By using parametric down-conversion process with a strong signal field injection, we demonstrate coherent frequency down-conversion from a pump photon to an idler photon. Contrary to a common misunderstanding, we show that the process can be free of quantum noise. With an interference experiment, we demonstrate that the coherence is preserved in the conversion process. This may lead to a high fidelity quantum state transfer from high frequency photon to low frequency photon and connects a missing link in a quantum network. With this scheme of coherent frequency down-conversion of photons, we propose a method of single-photon wavelength division multiplexing.
We report on the implementation of quantum frequency conversion (QFC) between infrared (IR) and ultraviolet (UV) wavelengths by using single-stage upconversion in a periodically poled KTP waveguide. Due to the monolithic waveguide design, we manage to transfer a telecommunication band input photon to the wavelength of the ionic dipole transition of Yb${}^{+}$ at 369.5 nm. The external (internal) conversion efficiency is around 5% (10%). The high energy pump used in this converter introduces a spontaneous parametric downconversion (SPDC) process, which is a cause for noise in the UV mode. Using this SPDC process, we show that the converter preserves non-classical correlations in the upconversion process, rendering this miniaturized interface a source for quantum states of light in the UV.