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Primeur weekly 2017-04-18

Quantum computing

QxBranch and Commonwealth Bank Australia launch quantum computing simulator ...

Indistinguishable photons key to advancing quantum technologies ...

Recent advances and new insights into quantum image processing ...

Focus on Europe

Teratec 2017 Forum issues Call for Participation ...

Hazel Hen helps explain ultrafast phase transition ...

Hardware

Engility to pursue NASA advanced computing services opportunity ...

DDN names Jessica Popp General Manager of IME business unit ...

Eni fires up its HPC3, the new hybrid high performance computer for E&P activities ...

DDN advances object storage performance and delivers industry's most flexible and cost-effective data protection ...

Asetek to receive RackCDU D2C order for new HPC installation ...

PSNC deploys ADVA Optical Networking 96-channel 100G core solution in pan-European research network ...

Putting a spin on logic gates ...

Tool for checking complex computer architectures reveals flaws in emerging design ...

System better allots network bandwidth, for faster page loads ...

Applications

SDSC to enhance campus research computing resources for bioinformatics ...

U.S. Department of Energy's INCITE programme seeks advanced computational research proposals for 2018 ...

Tutorials schedule announced for PEARC17 ...

Fujitsu awarded three prizes for science and technology from MEXT ...

Fujitsu and Grid partner to jointly develop AI services ...

IBM brings Anaconda Open Data Science platform to IBM Cognitive Systems ...

Jefferson Lab scientists eavesdrop on chatter of sub-atomic world ...

Buckle up - Climate change to increase severe aircraft turbulence ...

Beyond the frontiers of Supercomputing ...

Scientists develop a novel algorithm, inspired on the behaviour of bee colonies, which will help dismantling criminal social networks ...

The Cloud

Atos leads C2NET consortium - the first collaborative Cloud-based platform for SMEs to support manufacturing management ...

Comcast Business now provides enterprises with dedicated links to IBM Cloud ...

Nimbix ushers in next-generation GPUs for Cloud-based deep learning ...

USFlash

Group works toward devising topological superconductor ...

Stanford researchers create deep learning algorithm that could boost drug development ...

Biased bots: Human prejudices sneak into artificial intelligence systems ...

Indistinguishable photons key to advancing quantum technologies

11 Apr 2017 Washington, D.C. - Researchers in Japan are tapping nitrogen impurity centres found within gallium arsenide to generate indistinguishable photons, critical for quantum information processing. To really take off, advanced quantum information processing will require getting a better (experimental) grasp of an essential phenomenon called "indistinguishable photons". A high degree of "indistinguishability" requires almost complete wave-packet overlap, or perfect photon matching, of energy, space, time and polarization.

While many types of single-photon emitters such as semiconductor quantum dots have already demonstrated generation of indistinguishable photons, a group of researchers from the University of Tsukuba and Japan's National Institute for Materials Science looked to using a nitrogen impurity centre found in III-V compound semiconductors as a novel single-photon source. They report their results this week in the journalApplied Physics Letters, from AIP Publishing.

Nitrogen luminescence centers within III-V compound semiconductors, composed of elements in columns III and IV of the periodic table such as GaAs, show a sharp emission spectrum corresponding to an energy state known as an "isoelectronic trap". Single-photon generation from these isoelectronic traps is highly desirable because of the homogeneity it provides, emitting photons from multiple centers with the same energy.

"Our studies confirmed that isoelectronic traps do indeed have a long coherence time, which is one of the necessary conditions for creating an indistinguishable photon", stated Michio Ikezawa, an associate professor at Pure and Applied Sciences, University of Tsukuba.

For the study, the group first evaluated the indistinguishability of photons emitted from a luminescence center in nitrogen delta-doped GaAs by two-photon interference. They also investigated its time dependence, which revealed important information about the timescale of decoherence - said another way, when the quantum system blurs and displays classical state behaviour - that can be challenging to obtain via other methods.

For this work, the "emission centre" that acts as an iso-electronic trap is formed by the impurity within GaAs where nitrogen has replaced arsenic. "When the sample is photo-excited, each trap can capture one electron-hole pair and emit a single photon by a radiative recombination of them", Michio Ikezawa stated.

These nitrogen impurities are then "doped within a very thin two-dimensional layer by the so-called delta-doping technique during metal organic chemical vapor deposition growth", Michio Ikezawa stated. "Using this technique, a single luminescence center can be selected with a conventional optical microscope."

Measuring the indistinguishability offered surprising insight. "The indistinguishability was 0.24, which was independent of the time interval between 2 to 4 nanoseconds", Michio Ikezawa stated. "This was somewhat surprising compared with previous studies of quantum dots, and we concluded that there's a very fast dephasing mechanism within 2 nanoseconds in our sample."

The group's results are important not just because they are the first demonstration of measuring two-photon interference of indistinguishable photons created by impurity centres in III-IV semiconductors, but also because they explore similarities and differences with typical quantum dots for decoherence mechanisms.

As far as applications, "indistinguishable photons are very important for quantum information technology such as quantum teleportation and linear optical quantum computation", Michio Ikezawa stated. "Our goal is to be able to provide many photon sources that generate indistinguishable photons in an integrated form in a semiconductor chip."

While semiconductor quantum dots have been intensively studied with similar aims, "it's difficult in principle to make the energy of photons obtained from many quantum dots the same so that they're indistinguishable from each other", Michio Ikezawa stated. "The indistinguishability obtained this time wasn't high enough. It's thought to be caused by the high-speed relaxation mechanism we reported, so a future task will be to clarify the mechanism and find a method to suppress it."

The article, "Quantum interference of two photons emitted from a luminescence center in GaAs:N", is authored by Michio Iwezawa, Liao Zhang, Yoshiki Sakuma and Yasuaki Masumoto. The article has appeared in the journal Applied Physics Letters on April 11, 2017.
Source: American Institute of Physics - AIP

Back to Table of contents

Primeur weekly 2017-04-18

Quantum computing

QxBranch and Commonwealth Bank Australia launch quantum computing simulator ...

Indistinguishable photons key to advancing quantum technologies ...

Recent advances and new insights into quantum image processing ...

Focus on Europe

Teratec 2017 Forum issues Call for Participation ...

Hazel Hen helps explain ultrafast phase transition ...

Hardware

Engility to pursue NASA advanced computing services opportunity ...

DDN names Jessica Popp General Manager of IME business unit ...

Eni fires up its HPC3, the new hybrid high performance computer for E&P activities ...

DDN advances object storage performance and delivers industry's most flexible and cost-effective data protection ...

Asetek to receive RackCDU D2C order for new HPC installation ...

PSNC deploys ADVA Optical Networking 96-channel 100G core solution in pan-European research network ...

Putting a spin on logic gates ...

Tool for checking complex computer architectures reveals flaws in emerging design ...

System better allots network bandwidth, for faster page loads ...

Applications

SDSC to enhance campus research computing resources for bioinformatics ...

U.S. Department of Energy's INCITE programme seeks advanced computational research proposals for 2018 ...

Tutorials schedule announced for PEARC17 ...

Fujitsu awarded three prizes for science and technology from MEXT ...

Fujitsu and Grid partner to jointly develop AI services ...

IBM brings Anaconda Open Data Science platform to IBM Cognitive Systems ...

Jefferson Lab scientists eavesdrop on chatter of sub-atomic world ...

Buckle up - Climate change to increase severe aircraft turbulence ...

Beyond the frontiers of Supercomputing ...

Scientists develop a novel algorithm, inspired on the behaviour of bee colonies, which will help dismantling criminal social networks ...

The Cloud

Atos leads C2NET consortium - the first collaborative Cloud-based platform for SMEs to support manufacturing management ...

Comcast Business now provides enterprises with dedicated links to IBM Cloud ...

Nimbix ushers in next-generation GPUs for Cloud-based deep learning ...

USFlash

Group works toward devising topological superconductor ...

Stanford researchers create deep learning algorithm that could boost drug development ...

Biased bots: Human prejudices sneak into artificial intelligence systems ...