Universal Quantum computers, Analog Quantum computers and Annealers

In Dec 2015, US Intelligence Advanced Research Projects Activity (IARPA) program notified IBM that it would award its scientists a major multi-year research grant to advance the building blocks for a universal quantum computer.

A universal quantum computer uses quantum mechanics to process massive amounts of data and perform computations in powerful new ways not possible with today’s conventional computers. This type of leap forward in computing could one day shorten the time to discovery for life-saving cancer drugs to a fraction of what it is today; unlock new facets of artificial intelligence by vastly accelerating machine learning; or safeguard cloud computing systems to be impregnable from cyber-attack.

Above- Dwave Systems has a quantum annealer with 2000 qubits and maybe adjusting its design to achieve 10,000 to 20,000 qubits or more, there is work by Google, Facebook, IBM on analog quantum and universal quantum systems which should be at 50 qubits or more at the end of this year. 50 qubit universal quantum computers should be more powerful than 2000 qubit annealers.

Earlier this year, IBM scientists demonstrated critical breakthroughs to detect quantum errors by combining superconducting quantum bits (qubits) in lattices on computer chips – and whose quantum circuit design is the only physical architecture that can scale to larger dimensions.
The award is funded under the Logical Qubits (LogiQ) program of IARPA led by Dr. David Moehring. The LogiQ Program seeks to overcome the limitations of current quantum systems by building a logical qubit from a number of imperfect physical qubits.

Under the LogiQ program, IBM’s research team will continue to pursue the leading approach for building a universal quantum computer by using superconducting qubits. By encoding the superconducting qubits into a logical qubit, one should then be able to perform true quantum computation. These logical qubit designs will be foundational to future, more complex quantum computing systems.

Logical Qubits (LogiQ)

The LogiQ Program seeks to overcome the limitations of current multi-qubit systems by building a logical qubit from a number of imperfect physical qubits. LogiQ envisions that program success will require a multi-disciplinary approach that increases the fidelity of quantum gates, state preparation, and qubit readout; improves classical control; implements active quantum feedback; has the ability to reset and reuse qubits; and performs further system improvements.

Additionally, LogiQ seeks a modular architecture design of two coupled logical qubits that creates a flexible and feasible path to larger systems. Modular designs facilitate the incorporation of next-generation advances with minimal constraints, while maintaining or improving performance.

Multi-Qubit Coherent Operations (MQCO)

The Multi-Qubit Coherent Operations Program aims to resolve the technical challenges involved in fabricating and operating multiple qubits in close proximity. The main themes of the program include qubit fabrication and yield; cross talk within the multi-qubit system; incorporation of the controls necessary to operate multiple qubits; coupling qubits to generate a universal gate set for quantum operations; and minimizing the overall system footprint. The program is comprised of different technologies including atomic and solid state based qubits. The end goal of the program is to execute quantum algorithms using multiple qubits and to evaluate the performance using a metric that can scale to higher qubit numbers.

In July 2017, IBM released two quantum computing platforms.

1. the 16-qubit Quantum Experience universal computer.
2. The core of its IBM Q commercial system, is a 17-qubit commercial processor prototype.This vastly improves upon the existing 5-qubit Quantum Computers.

The research has gained much pace in recent years. Researchers are smashing down one barrier after the other. 2016 witnessed the development of a quantum logic gate with 99.9 percent precision (citation: The paper ‘High-Fidelity Quantum Logic Gates Using Trapped-Ion Hyperfine Qubits’ is published in Physical Review Letters). Further, researchers were able to successfully use microwave signals to encode the data used in quantum computing (citation: The paper ‘Integrated optical addressing of an ion qubit’ is published in Nature Nanotechnology). This offers a revolutionary new alternative to the optical solutions to store data. Researchers also produced far more stable qubits using silicon atoms, thereby allowing much longer time frame to perform calculations.