September 2014 Vol. 12 No. 9

View from the Top

• Masahide Oka, Senior Executive Vice President, NTT EAST

  

  Overview
  The telecommunications industry is going through rapid and dramatic changes, and NTT EAST is unveiling a series of innovative policies to cope with this challenging business environment. In this transition to a new mindset, we asked Masahide Oka, Senior Executive Vice President of NTT EAST, to explain to us the logic that the company should use in providing services and the stance that it should take in facing today’s challenges.

Feature Articles: Frontiers of Quantum Optics Research at NTT Basic Research Laboratories

• Photonic Quantum Information Technologies Explored by Quantum Optics Research

  

  Abstract
  The quantum nature of light provides us with a novel technology for information processing and communication that is based on the principle of quantum mechanics. The Optical Science Laboratory of NTT Basic Research Laboratories has been engaged in investigating photonic quantum information processing, which involves quantum cryptography and quantum computing. These Feature Articles present the current status of our research activities involving quantum optical state control and the underlying light-matter interaction.

• Photonic Quantum Information Devices Using Coupled-resonator Optical Waveguides

  

  Abstract
  Integrating a quantum circuit on a small photonic chip offers the promise of large-scale quantum information processing using photons. In this article, we review our research and development of integrated quantum information devices using silicon photonic crystal technology.

• Distribution of Entangled Photon Pairs over 300 km of Optical Fiber

  

  Abstract
  We describe our recent experiment on the distribution of time-bin entangled photon pairs over 300 km of optical fiber, which set a record for long-distance distribution of quantum information. This experiment was achieved by using a high-speed and high signal-to-noise ratio entanglement generation/evaluation setup consisting of periodically poled lithium niobate waveguides and superconducting single-photon detectors. We observed the violation of Bell’s inequality and thus confirmed that the entangled photon pairs preserved the quantum correlation after they were separated by 300 km of fiber.

• Rare-earth Epitaxial Films as a Platform for Quantum Information Manipulation

  

  Abstract
  Rare-earth ions in a solid form have discrete energy levels peculiar to the ionic species, and they are therefore expected to become an excellent platform material for quantum information manipulation. A promising candidate for this purpose is rare-earth epitaxial film such as erbium oxide (Er₂O₃) film grown on a silicon substrate. This article describes the high-quality crystal growth and excellent optical characteristics of Er₂O₃ epitaxial films for quantum information devices.

• Investigating the Properties of Glasses Using High Resolution Spectroscopy of Er³⁺ Ions

  

  Abstract
  We have been investigating hyperfine sublevels of ¹⁶⁷Er³⁺ ions doped in a silicate glass fiber with the objective of demonstrating quantum memory in the 1.5-μm telecommunication band. Memory time is determined by the stability of hyperfine sublevels (the lifetime) of ¹⁶⁷Er³⁺ ions, so it is therefore necessary to clarify the lifetime properties. This article describes (i) the anomalous temperature dependence of the lifetime that was unexpectedly discovered in the lifetime measurements and (ii) the physical properties of glass that resulted in the anomalous phenomenon.

• A Bose-Einstein Condensate Achieved on a Persistent-supercurrent Atom Chip

  

  Abstract
  A persistent-supercurrent atom chip is a quantum device designed with a view to transcending the limits of conventional technologies by employing some of the significant properties of quantum mechanics. We have applied this novel technique to achieve an atomic gas in a macroscopic quantum state in the vicinity of a solid-state surface. In this article, we review a technique for making an extremely stable Bose-Einstein condensate above a chip surface and describe our attempts to overcome several unpredicted problems introduced by superconductivity.

Regular Articles

• “hitoe”—A Wearable Sensor Developed through Cross-industrial Collaboration

  

  Abstract
  NTT succeeded in developing a novel composite material consisting of a flexible conductive fiber fabricated by coating fiber material such as silk with a conductive polymer (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate): PEDOT-PSS). A press release on this development was issued in February 2013. Then, in January 2014, after forming a tie-up with NTT DOCOMO to spearhead the development of related services, NTT jointly announced with Toray Industries, Inc. and NTT DOCOMO the development of this composite conductive fiber material under the brand name “hitoe”. This article introduces the technology behind the hitoe material and discusses future scenarios in which the biomedical signals measured by hitoe should prove useful.

Global Standardization Activities

• Standardization Efforts in IP Interconnect Specifications

  

  Abstract
  As the use of VoIP (voice-over-Internet protocol) telephone services continues to spread, it is becoming increasingly desirable to migrate the connections between communications carriers to IP technology (IP interconnection) rather than connecting them through the existing public switched telephone networks. We describe here the domestic and international trends in standardization of IP interconnection interfaces as well as the NTT initiatives in this area.

External Awards/Papers Published in Technical Journals and Conference Proceedings

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