July 2017 Vol. 15 No. 7

Feature Articles: A New Era in Quantum Information Processing Technologies

• The Arrival of a New Era in Quantum Information Processing Technologies

  

  Abstract
  Research on quantum information processing has progressed astoundingly in the past several years. Concepts totally different from before such as adiabatic computation, quantum measurements, and topological states have been introduced, expanding the possibility of applications. This article introduces recent developments in quantum information processing and discusses NTT’s research achievements as examples of the advances in this field.

• Quantum Neural Network for Solving Complex Combinatorial Optimization Problems

  

  Abstract
  Optimization of various social systems, including communication, traffic, and social networking systems, requires the solving of complex combinatorial optimization problems. In this article, we describe the recent progress achieved in developing a quantum neural network, a computer that finds solutions to combinatorial optimization problems using a network of degenerate optical parametric oscillators.

• Lossless Wavelength Conversion of Single Photons

  

  Abstract
  We demonstrated a new scheme for wavelength conversion of a single-photon wave packet for use in quantum information communication technologies. The scheme enables us to deterministically change the color and shape of a single-photon wave packet in a lossless manner. The scheme is directly applicable to single photons traveling in an optical fiber network and will be a key technology in developing a photonic wavelength interface for quantum networking.

• Demonstration of Realism Violation on a Macroscopic Scale

  

  Abstract
  In quantum mechanics, we can realize quantum superposition states, which cannot be understood by the usual common sense in our living world. In the microscopic world, such as that experienced by a single electron spin, superposition behavior has been experimentally confirmed. However, it is still controversial as to whether or not we can in principle observe such quantum phenomena in the macroscopic world. At NTT Basic Research Laboratories, we have experimentally tested such macroscopic quantum phenomena by using a macroscopic quantum device.

• Coherent Coupling between 4300 Superconducting Flux Qubits and a Microwave Resonator

  

  Abstract
  A superconducting flux qubit can be used as a magnetic field sensor, and this has potential applications in many fields such as medical science and biology. If we could realize an entanglement between the superconducting flux qubits, it is expected that such a device would show much better sensitivity than any existing magnetic field sensors. We introduce here our recent research along this direction.

• Creating New Two-dimensional Topological Insulators for Fault-tolerant Quantum Computing

  

  Abstract
  Two-dimensional topological insulators (2DTIs) pave the way to explore novel quasiparticles for fault-tolerant quantum computing and to create devices utilizing spin degree of freedom. However, host materials that realize 2DTIs have so far been limited to two systems. In this article, we propose a strained quantum well structure as a new 2DTI candidate and demonstrate that strain enhances the energy gap and leads to superior bulk insulation properties.

• Implementation Security of Quantum Key Distribution

  

  Abstract
  Quantum key distribution is the ultimate cryptography in that it is theoretically secure against any possible eavesdropping. This ultimate security is an attractive feature, and companies and organizations in several countries, including Japan, are working on the deployment of networks for quantum key distribution. However, further research is needed to achieve the ultimate practical security, rather than security in principle. In this article, we introduce our recent research activities toward achieving the ultimate practical security.

Regular Articles

• Heart Rate Measurement with Video Camera Based on Visible Light Communication

  

  Abstract
  We have developed a system based on optical camera communication and an encoding method that can transfer the heart rates (HRs) of multiple people with high precision. The system can potentially measure and transfer the HRs of hundreds of people with their positional information. The unique system is composed of HR sensor units and a conventional camera. It is presented here along with the novel event timing encoding method.

• Path Loss Model to Evaluate Interference for Small Cells between Different Floors

  

  Abstract
  NTT Access Network Service Systems Laboratories and NTT DOCOMO have been carrying out joint research and development (R&D) toward construction of the fifth-generation mobile communications system (5G). This article presents a path loss model developed as one of our R&D activities.

Global Standardization Activities

• Report on Progress of ITU-T Study Group 3 at the World Telecommunication Standardization Assembly 2016 (WTSA-16)

  

  Abstract
  The World Telecommunication Standardization Assembly 2016 (WTSA-16) was held in Yasmine Hammamet, Tunisia, from October 25 to November 3, 2016. The following is an outline of discussions on ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) Study Group 3 covered at WTSA-16.

Short Reports

• Report on NTT Group Exhibits at CeBIT 2017―Showcasing Cutting-edge Use of ICT at the World’s Largest Information Technology Trade Fair

  

  Abstract
  The NTT Group exhibited at CeBIT 2017, which ran for five days (March 20−24, 2017) in Hanover, Germany. In its first participation in 12 years, NTT showcased examples of its cutting-edge use of information and communication technology in a variety of industrial fields. The exhibits were presented in an easily comprehensible manner and were highly appreciated by visitors. This article introduces the main exhibits and visitors’ responses to them.

• NTT Communications to Deploy 400-Gbit/s Optical Transmission System for Datacenter Network Connections

External Awards/Papers Published in Technical Journals and Conference Proceedings

• External Awards/Papers Published in Technical Journals and Conference Proceedings