August 2015 Vol. 13 No. 882015

https://www.ntt-review.jp/archive/2015/201508.html

Feature Articles
Frontier Research on Lowdimensional Semiconductor Physics
Ultimate Control of Electronic Properties inLow-dimensional Semiconductors
High-speed Single-electron Transfer toward
High-accuracy Current Standards
Noise in Nanometer-scale Electronic Devices
Gate Tuning of Direct/Indirect Optical Transitions inSilicon
Microscopic Probing of Crystalline Electrons Using
Magnetic Resonance
Semiconductor Quantum Structures with Single-atomPrecision
Creating a Topological Insulator Using Semiconductor
Heterostructures

Regular Articles
Two-mode Squeezing in an Electromechanical Resonator
Improving User Capacity and Disaster Recovery Time in IP Telephone Service Systems
Development of High-capacity Protocol for M2M Services and Its Application to a Pallet
Management System

Global Standardization Activities
Reports of 4th ITU-T Review Committee and 1st FG-DFS (Digital Financial Services) Meetings

Practical Field Information about Telecommunication
Technologies
Case Studies of Faults and Countermeasures in Access Telephone Office

Feature Articles
Frontier Research on Low-dimensional Semiconductor Physics

Ultimate Control of Electronic Properties inLow-dimensional Semiconductors▼Abstract

Recent progress in semiconductor technology has enabled the development of structures that are scaled
down to the nanometer level with high precision by using highly sophisticated nanofabrication and crystal
growth techniques. Confining electrons to such low-dimensional nanostructures makes it possible toachieve precise control of electrons as particles as well as waves. The Feature Articles in this issue review
our recent research activities involving low-dimensional semiconductor devices that will be applied toachieve innovative electronics in future science and information and communication technologies.

Regular Articles

Two-mode Squeezing in an Electromechanical Resonator▼Abstract

A mechanical resonator integrated with piezoelectric transducers enables
mechanical nonlinearities to be dynamically engineered to emulate
non-degenerate parametric down-conversion. In this configuration,
millions of phonons are simultaneously generated in pairs in two
macroscopic vibration modes, which results in the amplification of theirmotion by more than 20 dB. Mechanical two-mode squeezed states arealso created in parallel, which exhibit fluctuations 5 dB below the thermal
level of their constituent modes and they harbor correlations between themodes that become perfect as their amplification is increased. This remarkable observation of correlations
between two massive phonon ensembles establishes the means to create an entangled macroscopic
mechanical system at the single phonon level.

Improving User Capacity and Disaster Recovery Time in
IP Telephone Service Systems▼Abstract

The NTT Group is working on improving Internet protocol (IP)telephone networks and solving certain problems associated withthem. Specifically, efforts are underway to improve the accommodation
rate, reduce network operating costs when the number of network
users increases, and reduce service recovery time when a network isdamaged because of a natural disaster. To resolve these problems, we developed a system architecturethat simplifies the operation of IP telephone networks and uses network equipment much more efficiently.
This is possible with a subscriber data management server. We describe here our new networkarchitecture, the mechanism to solve these problems, and the effect it has on IP telephone networks.

Development of High-capacity Protocol for M2M Servicesand Its Application to a Pallet Management System▼Abstract

NTT Network Innovation Laboratories has developed ahigh-capacity protocol for the 920-MHz band in order to enhancethe effectiveness and accelerate the adoption ofmachine-to-machine (M2M) services. This protocol can detect
the movement of hundreds of terminals and manage more than
10,000 terminals. The protocol is applied to physical distribution
systems in which very large inventories need to be controlled. It offers efficient management ofloading/unloading activities. The protocol was commercialized as a pallet management system in fiscal year
2015. In this article, we describe the protocol and explain how we verified its performance in tests
conducted in an actual goods distribution center.