A photoconductive antenna has an array of antenna electrodes on or in a photoconductive substrate. The photoconductive substrate is irradiated with light from a pulsed laser via micro-lenses above respective gaps between antenna electrodes. This makes the photoconductive substrate temporarily conductive, causing pulsed electric antenna currents that can be used for transmission of electromagnetic radiation in the Terahertz range. The bias circuit of the antenna is configured to determine voltages applied to the antenna electrodes by capacitive voltage division over a series of successive capacitors, each capacitor being formed by the antenna electrodes of a respective pair of successive ones of the antenna electrodes in the array as plates of the capacitor adjacent to a respective one of the gaps.

A system for transmission of quantum information for quantum error correction includes an ancilla qubit chip including a plurality of ancilla qubits, and a data qubit chip spaced apart from the ancilla qubit chip, the data qubit chip including a plurality of data qubits. The system includes an interposer coupled to the ancilla qubit chip and the data qubit chip, the interposer including a dielectric material and a plurality of superconducting structures formed in the dielectric material. The superconducting structures enable transmission of quantum information between the plurality of data qubits on the data qubit chip and the plurality of ancilla qubits on the ancilla qubit chip via virtual photons for quantum error correction.

A spread spectrum receiving method receives a spread spectrum signal. An optical signal frequency comb is generated. Modes of the optical signal frequency comb are modulated with a received spread spectrum signal. An optical local oscillator comb is generated that is mutually coherent with the signal frequency comb. A code word is applied to the local oscillator comb. The combs are combined and the received spread spectrum signal is detected from the combined combs.

A spread spectrum receiving method receives a spread spectrum signal. An optical signal frequency comb is generated. Modes of the optical signal frequency comb are modulated with a received spread spectrum signal. An optical local oscillator comb is generated that is mutually coherent with the signal frequency comb. A code word is applied to the local oscillator comb. The combs are combined and the received spread spectrum signal is detected from the combined combs.

A wireless communication device includes a quantum cascade laser (QCL) configured to generate a terahertz (THz) or microwave carrier signal. The QCL includes a laser waveguide, a laser optical gain medium incorporated in the laser waveguide, and at least one electrode. An antenna may be integrated with the electrode. The device may be a transmitter, the electrode configured to receive an input baseband signal, the QCL configured to couple the THz or microwave carrier signal and the input baseband signal into a THz or microwave communication signal, and the antenna configured to transmit the THz or microwave communication signal. The device may be a receiver, the antenna configured to receive a THz or microwave communication signal, and the QCL configured to de-couple the THz or microwave communication signal from the THz or microwave carrier signal into an output baseband signal.

Microwave photonic vector network analyzer and a method for measuring scattering parameters of a microwave device are provided. The analyzer comprises a microwave source, wherein a signal loading module, an optical sampling module and a signal processing module are sequentially arranged along a signal output direction of the microwave source; an output end of the signal processing module is respectively connected with a control end of the microwave source and a control end of the optical sampling module; and two test ports of the signal loading module are connected with both ends of a device to be tested. The invention realizes direct sampling and frequency conversion for microwave signals, abandons a superheterodyne structure and/or direct frequency conversion structure in the traditional network analyzer, simplifies the structure of the system while improving the measurement frequency range and avoiding image interference, and reduces system complexity, cost and power consumption.

A communication system and method is described, including two or more transceivers at different locations, in which a region of the atmosphere at an altitude ranging from 150-350 KM is modified by applying an E-Field strength of 0.2 V/m to create a High-Frequency Ionized Lines/High-Frequency Plasma Lines (HFIL/HFPL) region. The HFIL/HFPL region provides a means for incoming RF transmission signals to be isotropically repeated and received by transceivers at other distant locations within line-of-sight of the HFIL/HFPL region. Incoming RF transmissions into the HFIL/HFPL region may use radio frequencies ranging from 100 MHz-20 GHz. The system described offers a means for users to transmit data from one over-the-horizon location to another at distances up to 4800 km without wires or physical satellites.

A communication system and method is described, including two or more transceivers at different locations, in which a region of the atmosphere at an altitude ranging from 150-350 KM is modified by applying an E-Field strength of 0.2 V/m to create a High-Frequency Ionized Lines/High-Frequency Plasma Lines (HFIL/HFPL) region. The HFIL/HFPL region provides a means for incoming RF transmission signals to be isotropically repeated and received by transceivers at other distant locations within line-of-sight of the HFIL/HFPL region. Incoming RF transmissions into the HFIL/HFPL region may use radio frequencies ranging from 100 MHz-20 GHz. The system described offers a means for users to transmit data from one over-the-horizon location to another at distances up to 4800 km without wires or physical satellites.

A spread spectrum receiver and receiving methods are provided. Received data is physically reconstructed in the optical domain using a pair of coherently coupled frequency combs, one modulated by the received signal and one modulated by the code word, and then detecting the received data with a subrate detector comprised of detector array. Particular methods and receivers extract a timing difference between the received spread spectrum signal and the codeword from the phase shifts of Fourier terms of the product of the received spread spectrum signal and the codeword that can be measured from the combined combs.

A spread spectrum receiver and receiving methods are provided. Received data is physically reconstructed in the optical domain using a pair of coherently coupled frequency combs, one modulated by the received signal and one modulated by the code word, and then detecting the received data with a subrate detector comprised of detector array. Particular methods and receivers extract a timing difference between the received spread spectrum signal and the codeword from the phase shifts of Fourier terms of the product of the received spread spectrum signal and the codeword that can be measured from the combined combs.