Useful properties of a Quantum Neural Network

Why would someone go to the time and expense of trying to build a Quantum Neural Network (QNN)?  In other words, even if it is possible to do so, what is it useful for?

 1. You can run a quantum Turing machine on a QNN.  A quantum Turing machine is the basis for quantum computing (QC).  One thing we know QC can do is easily and rapidly crack public key cryptography.  Anyone with access to a QC can read other people's (encrypted) mail, which is the primary purpose of several Government agencies.  No other reason is required, from the perspective of e.g. NSA, to spend billions trying to build one, even if the chance of success is quite low.  This works best if the QC remains a secret, because QC can not crack encryption done the old-fashioned way: shared secret keys, transmitted offline, and synchronous encryption.

2.  A whole host of new technologies can be derived from a QNN.  A QNN is, in fact, a new General Purpose Technology, a technology that enables other new technologies.  Some examples of other General Purpose Technologies include: fire, agriculture, combustion engine, electricity, radio, chemistry, mechanization.  This author suspects this factor was not a consideration by the people who may have funded this project, as it is not at all obvious that QNN is a new General Purpose Technology.  It is, though.  Below are some new technologies enabled by practical QNN technology.

3.  A QNN can be the basis of Advanced Artificial Intelligence.  A QNN is a physical-system starting point for artificial brain technology.  This has many valuable and important uses in both military and civilian life.  Advanced AI enables many new technologies.  E.g.  self-driving vehicles, Jeopardy-winning computers, automatic language translation, extreme data compression rates,  improved data-mining, digital personal assistance, et cetera.

4.  A QNN can provide a secret communications system.  The system provides a quantum channel that effectively teleports information from Alice directly to Bob.  Alice and Bob would each need to be near a Node of the QNN, using a conventional computer with an oracular connection to the QNN.  There must be a (steganographic) classical back channel.  This system is probably quite scale-able.  This system could be used to securely distribute cryptographic keys for symmetric cryptography (e.g. AES), which can not be broken by any known algorithm, quantum or classical.

5.  A QNN might behave as a room temperature superconductor, but only for very tiny currents.

6.  A QNN would be a great starting basis for adiabatic (reversible) computing.  This would be one way to overcome an expected impending quantum limit to Moore's Law.

7.  QNN technology provides an excellent basis for developing, implementing, and securing advanced nanotechnology.

8.  QNN technology might be helpful in the field of Energy Resources, in several different ways.

9.    A QNN could be trained to drastically improve the effectiveness and range of quantum teleportation. The current 'official' range limit for quantum teleportation is about 16,000 meters.  This author supposes that QNN-enhanced quantum teleportation has a much greater range, probably enough range to reach satellites in orbit.