A quantum walk is the quantum mechanical analog of a classical random walk, describing the propagation of quantum walkers (photons) through an optical circuit. Because quantum walks generate large-scale quantum superposed states, they can be used for simulating many-body quantum systems and the development of algorithms for quantum computation. Nejadsattari et al. describe the photonic simulation with cyclic quantum systems. With the ability to simulate a variety of different quantum operations and gates, they claim that the versatility of the approach should allow the study of more complex many-body systems.
That might not sound like much, but in the quantum computing arms race, several groups are edging past one another as they aim to eventually make a universal quantum computer. A group of researchers at the Joint Quantum Institute has created a quantum simulator using 53 quantum bits, or qubits. Earlier this month, IBM announced a 50-qubit prototype, though its capabilities are unclear. With this 53-qubit device, the researchers have done scientific simulations that don't seem to be possible
IBM continues to push its quantum computing efforts forward and today announced that it will soon make a 53-qubit quantum computer available to clients of its IBM Q Network. The new system, which is scheduled to go online in the middle of next month, will be the largest universal quantum computer available for external use yet. The new machine will be part of IBM's new Quantum Computation Center in New York State, which the company also announced today. The new center, which is essentially a data center for IBM's quantum machines, will also feature five 20-qubit machines, but that number will grow to 14 within the next month. IBM promises a 95% service availability for its quantum machines.
Intel is taking a slow and steady approach to quantum computing. Competitors like Google may be racing to achieve so-called quantum supremacy, in which a quantum computer outperforms an ordinary one. But Intel's James Clarke has bigger ideas. He leads the firm's quantum computing research team, and says it is looking past near-term goals in order to be the first to make a device with a million qubits, or quantum bits – enough to have a real impact on the world.
The first third of the 20th century saw the collapse of many absolutes. Albert Einstein's 1905 special relativity theory eliminated the notion of absolute time, while Kurt Gödel's 1931 incompleteness theorem questioned the notion of absolute mathematical truth. Most profoundly, however, quantum mechanics raised doubts on the notion of absolute objective reality. Is Schrödinger's cat dead or alive? Nearly 100 years after quantum mechanics was introduced, scientists still are not in full agreement on what it means.