Another Open Access Quantum Computer Goes Live on November 27, 2017

NTT, Japan’s National Institute of Informatics, and the University of Tokyo will be putting on-line what they call a “Quantum Neural Network” machine starting November 27th.   This machine is not a general purpose gate-based quantum computer, but rather one designed for optimizing Ising models similar to the approach taken by D-Wave with their quantum annealing machine.  There will not be any charge initially for access to this machine, although these organizations are intending on offering a commercialized version by 2020.  The design of this machine is quite unique due to the following factors:

·      The qubits are implemented using photonics with pulses of light that circulate in a 1Km fiber optic cable.

·      This machine runs at room temperature and does not require a dilution refrigerator.  As a result power consumption is only 1 Kilowatt.

·      The machine will initially be implemented with 2000 qubits, but the design appears to be easily scalable to higher capacities with a goal of reaching 100,000 qubits by March 2019.

·      The Ising optimization models require programming the level of interaction between different qubits and the connectivity between qubits is a very important factor.   While the D-Wave machine currently is only able to connect each qubit to six or less neighboring qubits, there does not seem to be any connectivity limits in this “Quantum Neural Network” machine.  This could potentially provide a large advantage for fitting in problems within the constraints of the machine.

As a result, the architecture of this photonic based “Quantum Neural Network” machine could theoretically have a large advantage over the superconducting quantum annealing approach used by D-Wave.  However, we will need to see if this architecture can realize these advantages in actuality after researchers have had a chance to try it out.  For more details on this machine you can read a technical paper (in Japanese) here and a video that explains the architecture here.   After November 27th, you will be able to try out the machine for yourself by going to

Marco Paini
@ 3:35 am


Do you have a reference/paper that talks about NTT’s plan to scale to 100k qubits by March 2019? I would like to check if that’s been updated or if they are still on track to hit that target

Many thanks

    @ 12:32 pm

    You can find a paper from NTT that describes the system and their goal to increase the system size by more than 10X on the SPIE web site at (See the last paragraph).

    I can no longer find the specific reference to the 100K level anymore. Perhaps it was taken off the web. But I do remember they were proposing to accomplish this by increasing the length of the 1 Km fiber optic cable loop and reducing the time between pulses.

    I will also point out that the concept of the Quantum Neural Network (also called Coherent Ising Machines) is still a little controversial. You can find a paper published in June 2018 on arXiv by D-Wave that discusses this at

    Doug Finke
    Managing Editor

      marco paini
      @ 7:38 am

      Thank you!!


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