The Intelligence Advanced Research Projects Activity (IARPA), the research arm of US intelligence, is launching the Logical Qubits (LogiQ) research program to overcome the current practical limitations of quantum computing.
Quantum computers may theoretically be able to solve certain problems – including code breaking – much faster than classical computer and perform computations that would be otherwise impossible. This explains the enthusiasm of researchers and venture capitalists for the first quantum computing demonstrations. Now that the intelligence community wants to harness the power of quantum computing for its challenging data processing requirements, it is important to move beyond the research stage and build operational, fault tolerant, scalable quantum computers.
Encoding Imperfect Physical Qubits Into a ‘Perfect’ Logical Qubit
Quantum computers encode information in “qubits” that can be in a quantum superposition of zero and one states, and therefore they can process information in ways that have no equivalent in classical computing by exploiting subtle quantum phenomena such as quantum entanglement. The theoretical peak performance of quantum computers increases very fast with the number of qubits – but so does the engineering challenge of building quantum processors.
Building operational high-performance quantum computers is complicated by qubit instability and sensitivity to environmental noise. Therefore, IARPA is looking for efficient error correction techniques and ways to scale quantum computing systems to large numbers of qubits.
In particular, 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. The IARPA presentation for potential research partners states that:
LogiQ seeks to demonstrate a single logical qubit with longer coherence times and lower gate infidelities than its constituent physical qubits.
Researchers at IARPA and IBM have been working on logical qubits, FCW reports. IBM scientists announced in April that they had developed a new qubit circuit design that is the only physical architecture that could successfully scale to larger dimensions.
“[Quantum information processing] still suffers from physical-qubit gate and measurement fidelities that fall short of desired thresholds, multi-qubit systems whose overall performance is inferior to that of isolated qubits, and non-extensible architectures – all of which hinder their path toward fault-tolerance,” states the LogiQ program information page. “In order to capture the full range of issues that impact the development of a larger quantum processor, it is important to focus on improving all of these aspects concurrently.”
IARPA said the LogiQ Program would begin Feb. 1, 2016, and end by Jan. 31, 2021. IARPA is now seeking creative technical solutions to the challenge of encoding imperfect physical qubits into a logical qubit that protects against decoherence, gate errors, and deleterious environmental influences. The deadline for the initial round of proposals is Sept. 1.
Images from IBM and Creativity103/Flickr.