At Xanadu we are developing a photonic quantum computer: a device that processes information stored in quantum states of light. We are very excited by the possibilities that this approach brings. Photonic quantum computers naturally use continuous degrees of freedom -- like the amplitude and phase of light -- to encode information. This continuous, or analog, structure makes photonic devices a natural platform for quantum versions of neural networks. How do we mimic a neural network using a photonic system?
This work presents a novel fundamental algorithm for for defining and training Neural Networks in Quantum Information based on time evolution and the Hamiltonian. Classical Neural Network algorithms (ANN) are computationally expensive. For example, in image classification, representing an image pixel by pixel using classical information requires an enormous amount of computational memory resources. Hence, exploring methods to represent images in a different paradigm of information is important. Quantum Neural Networks (QNNs) have been explored for over 20 years. The current forefront work based on Variational Quantum Circuits is specifically defined for the Continuous Variable (CV) Model of quantum computers. In this work, a model is proposed which is defined at a more fundamental level and hence can be inherited by any variants of quantum computing models. This work also presents a quantum backpropagation algorithm to train our QNN model and validate this algorithm on the MNIST dataset on a quantum computer simulation.
Maybe quantum computing is a job for artificial intelligence. To call quantum computing complicated is a gross understatement. Rather than any single complex challenge, quantum computing is a series of obstacles all superimposed (pun intended) onto each other. Even though quantum processors based on superconducting circuits already exist in labs today, they don't compare in speed or processing power to today's typical desktop, laptop, and tablet computers. Even if you can settle on materials, a physical architecture, and a form factor for your quantum device, you're still faced with the very real difficulties of actually measuring quantum signals so you can take advantage of the processing and storage enhancements offered by quantum computing.
A new paradigm of quantum computing, namely, soft quantum computing, is proposed for nonclassical computation using real world quantum systems with naturally occurring environment-induced decoherence and dissipation. As a specific example of soft quantum computing, we suggest a quantum neural network, where the neurons connect pairwise via the "controlled Kraus operations", hoping to pave an easier and more realistic way to quantum artificial intelligence and even to better understanding certain functioning of the human brain. Our quantum neuron model mimics as much as possible the realistic neurons and meanwhile, uses quantum laws for processing information. The quantum features of the noisy neural network are uncovered by the presence of quantum discord and by non-commutability of quantum operations. We believe that our model puts quantum computing into a wider context and inspires the hope to build a soft quantum computer much earlier than the standard one.
European quantum physicists have done some amazing things over the past few decades: sent single photons to Earth orbit and back, created quantum bits that will be at the heart of computers that can crack today's encryption, and "teleported" the quantum states of photons, electrons, and atoms. But they've had less success at turning the science into technology. At least that's the feeling of some 3,400 scientists who signed the "Quantum Manifesto," which calls for a big European project to support and coordinate quantum-tech R&D. The European Commission heard them, and answered in May with a 1 billion, 10-year-long megaproject called the Quantum Technology Flagship, to begin in 2018. "Europe had two choices: either band together and compete, or forget the whole thing and let others capitalize on research done in Europe," says Anton Zeilinger, a physicist at the University of Vienna who did breakthrough work in quantum teleportation, which would be key to a future Internet secured by quantum physics.