arXiv subjects

Yanjun Ma

Publications and source records attributed to Yanjun Ma.

41 records · Page 3Linked to original sources

arXiv2012

On the Achievability of Interference Alignment for Three-Cell Constant Cellular Interfering Networks

For a three-cell constant cellular interfering network, a new property of alignment is identified, i.e., interference alignment (IA) solution obtained in an user-cooperation scenario can also be applied in a non-cooperation environment. By using this property, an algorithm is proposed by jointly designing transmit and receive beamforming matrices. Analysis and numerical results show that more degree of freedom (DoF) can be achieved compared with conventional schemes in most cases.

cs.IT↗

arXiv2011

Distributed Interference Alignment with Low Overhead

Based on closed-form interference alignment (IA) solutions, a low overhead distributed interference alignment (LOIA) scheme is proposed in this paper for the $K$-user SISO interference channel, and extension to multiple antenna scenario is also considered. Compared with the iterative interference alignment (IIA) algorithm proposed by Gomadam et al., the overhead is greatly reduced. Simulation results show that the IIA algorithm is strictly suboptimal compared with our LOIA algorithm in the overhead-limited scenario.

cs.IT↗

arXiv2010

Group Based Interference Alignment

In the $K$-user single-input single-output (SISO) frequency-selective fading interference channel, it is shown that the maximal achievable multiplexing gain is almost surely $K/2$ by using interference alignment (IA). However, when the signaling dimensions are limited, allocating all the resources to all users simultaneously is not optimal. So, a group based interference alignment (GIA) scheme is proposed, and it is formulated as an unbounded knapsack problem. Optimal and greedy search algorithms are proposed to obtain group patterns. Analysis and numerical results show that the GIA scheme can obtain a higher multiplexing gain when the resources are limited.

cs.IT↗

arXiv2010

Rewritable nanoscale oxide photodetector

Nanophotonic devices seek to generate, guide, and/or detect light using structures whose nanoscale dimensions are closely tied to their functionality. Semiconducting nanowires, grown with tailored optoelectronic properties, have been successfully placed into devices for a variety of applications. However, the integration of photonic nanostructures with electronic circuitry has always been one of the most challenging aspects of device development. Here we report the development of rewritable nanoscale photodetectors created at the interface between LaAlO3 and SrTiO3. Nanowire junctions with characteristic dimensions 2-3 nm are created using a reversible AFM writing technique. These nanoscale devices exhibit a remarkably high gain for their size, in part because of the large electric fields produced in the gap region. The photoconductive response is gate-tunable and spans the visible-to-near-infrared regime. The ability to integrate rewritable nanoscale photodetectors with nanowires and transistors in a single materials platform foreshadows new families of integrated optoelectronic devices and applications.

cond-mat.mes-hall↗

arXiv2008

Intrinsic Quantum Noise in Faraday Rotation Measurements of a Single Electron Spin

Faraday rotation is one way to realize quantum non-demolition measurement of electron spin in quantum dots. To describe Faraday rotation, semiclassical models are typically used, based on quantized electron spin states and classical electromagnetic fields. Such treatments neglect the entanglement between electronic and photonic degrees of freedom that produce intrinsic quantum noise, limiting the ultimate sensitivity of this technique. We present a fully quantum-mechanical description of Faraday rotation, and quantify this intrinsic noise. A method for measuring the purity of a given spin state is suggested based on this analysis.

quant-ph↗