Basis pursuit of sparse decomposition is adopted to discriminate and identify the target echo with two kinds of mainlobe jamming named time-delay repeater jamming and smeared spectrum (SMSP) jamming, ...which can produce multiple false targets. The main idea is to extract their pulsed differences. The signal model is first transformed to an underdetermined matrix equation, the dictionary is constructed by the function form of the target echo, and then the matrix equation is solved by replacing the l0 norm problem via the l1 norm problem. The identification of time-delay repeater jamming and the target echo is by the difference of the pulse width. Identifying SMSP jamming and the target echo is by the difference of the chirp rate. The proposed algorithm is particularly relevant to the case that the signals are overlapped. Finally, simulation results demonstrate the efficacy of the proposed method and they show that the method outperforms the conventional time–frequency representation method.
This paper proposes a wireless power repeater system for long-distance and multiple-load applications with equal power load at each repeater. Each repeater performs as a power relay that not only ...receives and transmits power but also supplies power to its local load. The main contribution of this paper is to provide the design methodology of a distributed power-relay system. First, it provides the mathematical model of the power distribution among the power relays, indicating that the inductances and resistances can affect the power distribution. Second, it provides the power transfer capability of a power-relay system based on the quality factor and efficiency requirement, indicating the maximum achievable number of power relays in a system. Aiming at practical applications, this paper provides the guideline for the circuit parameter design to achieve equal power distribution. Two typical examples are proposed to realize equal power distribution. The identical M n and different R n examples are selected for implementation. The coil size is 400 mm × 400 mm, and the eight power relays achieve a transfer distance of 3.2 m with a total power of 760 W and an efficiency of 70%. Experimental results validate that equal power distribution is achieved for the multiple loads across a long distance. Each power relay dissipates about 95-W power in its local load with a power variation limited to ±2%.
We describe principles of operation of a quantum repeater, i.e., a device designed to distribute entangled states of quantum systems over long distances. A review is presented of the latest ...achievements in the field of experimental implementation of its simplest version (a first-generation quantum repeater) and in the development of its key component (quantum memory). The immediate and long-term prospects for the development of studies in this area are discussed.
Electrodiagnostic (EDx) studies play a key role in the investigation of suspected Guillain‐Barré syndrome (GBS), providing diagnostic and prognostic information. However, initial EDx findings may not ...fulfill the neurophysiological criteria for the disease. The aim of this study was to estimate the occurrence and characteristics of A‐waves and repeaters F‐waves (Freps), both late motor responses identical in latency and configuration, in early stages of GBS. We retrospectively analyzed the initial nerve conduction study (NCS) of 26 GBS patients performed within 10 days from symptom onset. The final subtype diagnosis was acute inflammatory demyelinating polyneuropathy (AIDP) in 16 patients (six met the criteria at the initial EDx study and 10 at follow‐up) and acute motor axonal neuropathy (AMAN) in 10 patients (six initially). Identical late responses were commonly found in the majority of nerves (84%). A‐waves were present in 59% and an increased frequency of Freps was calculated in 61% of the 105 studied nerves. A‐waves morphology (single or complex) could not distinguish between AIDP and AMAN. Nerves with normal NCS had a significantly higher frequency of A‐waves, either isolated or in combination with increased index total Freps, as compared to nerves with low compound muscle action potential (CMAP) amplitudes or conduction block. Our findings suggest that both late responses can be useful as early markers of conduction changes of various pathophysiology, being frequently present even prior to abnormalities of CMAP parameters.
The false targets generated by interrupted sampling repeater jamming (ISRJ) bring serious threats to radar target detection and imaging. Transmitted waveform design with joint processing has become a ...promising way to deal with them. In this letter, the ambiguity function (AF) of the integral power frequency modulated (PFM) waveform is derived. Meanwhile, the time-frequency characteristic of the ISRJ signal received by the radar is analyzed on the range-Doppler plane. In consideration of the range-Doppler coupling characteristic, an improved Doppler filtering processing method is proposed to suppress the jamming of false targets. Simulation results demonstrate that the selected PFM waveform with the proposed joint processing method can effectively suppress the false targets resulting from ISRJ.
Advances in single-photon creation, transmission, and detection suggest that sending quantum information over optical fibers may have losses low enough to be correctable using a quantum error ...correcting code (QECC). Such error-corrected communication is equivalent to a novel quantum repeater scheme, but crucial questions regarding implementation and system requirements remain open. Here we show that long-range entangled bit generation with rates approaching 108 entangled bits per second may be possible using a completely serialized protocol, in which photons are generated, entangled, and error corrected via sequential, one-way interactions with as few matter qubits as possible. Provided loss and error rates of the required elements are below the threshold for quantum error correction, this scheme demonstrates improved performance over transmission of single photons. We find improvement in entangled bit rates at large distances using this serial protocol and various QECCs. In particular, at a total distance of 500 km with fiber loss rates of 0.3 dB km−1, logical gate failure probabilities of 10−5, photon creation and measurement error rates of 10−5, and a gate speed of 80 ps, we find the maximum single repeater chain entangled bit rates of 51 Hz at a 20 m node spacing and 190 000 Hz at a 43 m node spacing for the 3 , 1 , 2 3 and 7 , 1 , 3 QECCs respectively as compared to a bare success rate of 1 × 10−140 Hz for single photon transmission.
In this paper, we argue that communication at the speed of light (CaSoL) through on-chip copper interconnects is possible in the near future based on giga-scale integration (GSI) technologies. A ...three-step algorithm is introduced to design the optimum buffers in such systems. HSPICE simulations show that a <inline-formula> <tex-math notation="LaTeX">1.3\times </tex-math></inline-formula> time of flight (<inline-formula> <tex-math notation="LaTeX">{T}_{\text {F}} </tex-math></inline-formula>) is reachable in 7-nm FinFET technology. It is also shown that such a design is by nature, robust, and immune to process variations and crosstalk noise.
This letter deals with a novel transmitted scheme for a multisubcarrier frequency multiple-input multiple-output (MIMO)-synthetic aperture radar (SAR) system, which aims at suppressing the intrapulse ...repeater mainlobe-jamming and immensely improving the dynamic range of the receiver. To this end, due to the multisubcarrier frequency transmission scheme, the mixed signal with true target signal and repeater jamming can be separated by a well-designed spatial-frequency filter. Thus, the range and direction of arrival (DOA) information is accurately estimated without interrupting the normal work of the radar. Furthermore, to further improve the orthogonality of transmitted waveform, the design of a phase-coded LFM waveform pair exhibiting both low cross correlation energy (CCE) and low peak to sidelobe ratios (PSLRs), is considered. Besides, to handle the resulting nondeterministic polynomial (NP) hard problem, an alternating direction multiplier method (ADMM) based optimization method is employed. Compared with the traditional jamming suppression method, the proposed method improves the degree of freedom (DOF) from the carrier frequency domain, and it has the capability to suppress the intrapulse repeater mainlobe-jamming. Finally, detailed simulation experiments are carried out to verify the practicability and effectiveness of the newly proposed transceiver schemes.
Teleportation of entanglement over 143 km Herbst, Thomas; Scheidl, Thomas; Fink, Matthias ...
Proceedings of the National Academy of Sciences - PNAS,
11/2015, Letnik:
112, Številka:
46
Journal Article
Recenzirano
Odprti dostop
As a direct consequence of the no-cloning theorem, the deterministic amplification as in classical communication is impossible for unknown quantum states. This calls for more advanced techniques in a ...future global quantum network, e.g., for cloud quantum computing. A unique solution is the teleportation of an entangled state, i.e., entanglement swapping, representing the central resource to relay entanglement between distant nodes. Together with entanglement purification and a quantum memory it constitutes a so-called quantum repeater. Since the aforementioned building blocks have been individually demonstrated in laboratory setups only, the applicability of the required technology in real-world scenarios remained to be proven. Here we present a free-space entanglement-swapping experiment between the Canary Islands of La Palma and Tenerife, verifying the presence of quantum entanglement between two previously independent photons separated by 143 km. We obtained an expectation value for the entanglement-witness operator, more than 6 SDs beyond the classical limit. By consecutive generation of the two required photon pairs and space-like separation of the relevant measurement events, we also showed the feasibility of the swapping protocol in a long-distance scenario, where the independence of the nodes is highly demanded. Because our results already allow for efficient implementation of entanglement purification, we anticipate our research to lay the ground for a fully fledged quantum repeater over a realistic high-loss and even turbulent quantum channel.
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