Complete Noise Model Research Articles

99.92%-Fidelity cnot Gates in Solids by Noise Filtering.

Inevitable interactions with the reservoir largely degrade the performance of entangling gates, which hinders practical quantum computation from coming into existence. Here, we experimentally demonstrate a 99.920(7)%-fidelity controlled-not gate by suppressing the complicated noise in a solid-state spin system at room temperature. We found that the fidelity limited at 99% in previous works results from considering only static classical noise, and, thus, in this work, a complete noise model is constructed by also considering the time dependence and the quantum nature of the spin bath. All noises in the model are dynamically corrected by an exquisitely designed shaped pulse, giving the resulting error below 10^{-4}. The residual gate error is mainly originated from the longitudinal relaxation and the waveform distortion that can both be further reduced technically. Our noise-resistant method is universal and will benefit other solid-state spin systems.

Noise Wave Modeling of an SIS Mixer and Its IF Circuit Using Tucker's Quantum Theory of Mixing

Tucker's Quantum Theory of Mixing (QTM) is widely used to model the conversion gain and noise temperature of SIS mixers. In particular, the theory describes the phenomenon of non-classical conversion gain and that of infinite or even negative output impedances in inductively tuned SIS mixers. Common microwave noise theory is inadequate to describe the operation of the IF circuit connected to such mixers. In this paper, we report the use of the noise wave formalism to model the noise properties of a Double-Side-Band SIS mixer together with an IF isolator and low noise amplifier cascade. Starting from QTM, we derive the 4 noise parameters of the SIS mixer, together with an approximate 2-port chain matrix with an upper-side-band RF input port and an IF output port. These matrices are cascaded with the noise correlation matrix of the IF circuit to form a complete noise model of the SIS receiver. Optimum source impedance for the receiver can be derived from this noise model, which can be used in efficient CAD modeling of a complete SIS receiver.

Noise model for low-frequency through-the-Earth communication

[1] Analysis and simulation of through-the-Earth communication links and signal processing techniques require a more complete noise model than is needed for the analysis of conventional communication systems. This paper presents a multicomponent noise model that includes impulsive characteristics, direction-of-arrival characteristics, and effects of local geology. The noise model is derived from theoretical considerations and confirmed by field tests.

A model for measurement of noise in CCD digital-video cameras

This study presents a comprehensive measurement of CCD digital-video camera noise. Knowledge of noise detail within images or video streams allows for the development of more sophisticated algorithms for separating true image content from the noise generated in an image sensor. The robustness and performance of an image-processing algorithm is fundamentally limited by sensor noise. The individual noise sources present in CCD sensors are well understood, but there has been little literature on the development of a complete noise model for CCD digital-video cameras, incorporating the effects of quantization and demosaicing.

Small-signal and temperature noise model for MOSFETs

The present CMOS technology provides n-channel MOSFETs with a transit frequency beyond 30 GHz, which are attractive for RF integrated circuits, e.g., low-noise amplifiers. This paper presents an improved deembedding procedure for extraction of parasitic elements of MOSFETs. The extraction determines the intrinsic elements of the small-signal equivalent circuit. As a result, a new method to determine the gate capacitance is presented. This deembedding procedure is based on an analytical solution of the equations and facilitates the determination of the elements at any specific frequency. Moreover, a temperature noise model is presented, which is based on the small-signal equivalent circuit with an analytical description of the channel noise. This enables a complete noise modeling of all four noise parameters and the determination of the dominant noise sources. Finally, the noise-figure measurements are compared with the simulation results.

Three-stage wavelength converter based on cross-gain modulation in semiconductor optical amplifiers

A new cascaded three-stage all-optical wavelength converter based on cross-gain modulation (XGM) was analyzed and implemented using semiconductor optical amplifiers (SOAs) in a co-propagating arrangement. The optimal input powers of both pump and probe signals and the attenuation between the stages are discussed to achieve the highest on-to-off extinction ratio in each stage. A complete noise model was developed to calculate the bit error rate (BER), which is in good agreement with the experimental results. Power penalty free operation was achieved with the three-stage up-wavelength converter.