A new theoretical approach to quantum computing hardware has been proposed that could potentially revolutionize the field. The approach circumvents many of the problematic complexities found in current quantum computers and instead implements an algorithm in natural quantum interactions to process a variety of real-world problems faster than classical computers or conventional gate-based quantum computers can.
Natural Quantum Interactions
The Los Alamos National Laboratory team behind the approach has found that natural systems, such as the electronic spins of defects in diamonds, have precisely the type of interactions needed for their computation process. This eliminates many of the challenging requirements for quantum hardware, according to Nikolai Sinitsyn, a theoretical physicist at Los Alamos National Laboratory and co-author of the paper on the approach.
Simple Magnetic Field
The new strategy uses a simple magnetic field to rotate the qubits, such as the spins of electrons, in a natural system. Instead of setting up a complex system of logic gates among a number of qubits that must all share quantum entanglement, the precise evolution of the spin states is all that is needed to implement the algorithm. Sinitsyn said the approach could be used to solve many practical problems proposed for quantum computers.
The team proved that such operations can be made fast and that their approach is topologically protected. That is, it is robust against many errors in the precision of the control fields and other physical parameters even without quantum error correction. This is a significant step forward in quantum computing, as entanglement breaks down in a process known as decoherence, as the entangled qubits begin to interact with the world outside the quantum system of the computer, introducing errors. That happens quickly, limiting the computation time. True error correction has not yet been implemented on quantum hardware.
The Los Alamos team’s theoretical paper showed how the approach could solve a number-partitioning problem using Grover’s algorithm faster than existing quantum computers. Grover’s algorithm allows unstructured searches of large data sets that gobble up conventional computing resources. For instance, Grover’s algorithm can be used to divvy up the runtime for tasks equally between two computers, so they finish at the same time, along with other practical jobs. The algorithm is well-suited to idealized, error-corrected quantum computers, although it is difficult to implement on today’s error-prone machines.
Collaboration with Experimental Physicists
The team hopes to collaborate with experimental physicists at Los Alamos to demonstrate their approach using ultracold atoms. Modern technologies in ultracold atoms are sufficiently advanced to demonstrate such computations with about 40 to 60 qubits, which is enough to solve many problems not currently accessible by classical, or binary, computation. A qubit is the basic unit of quantum information, analogous to a bit in familiar classical computing.
Quantum computing remains a nascent field handicapped by the difficulty of connecting qubits in long strings of logic gates and maintaining the quantum entanglement required for computation. The new approach relies on natural rather than induced entanglement, so it requires fewer connections among qubits. That reduces the impact of decoherence. Thus, the qubits live for relatively a long time, according to Sinitsyn.
The new quantum computing paradigm proposed by the Los Alamos National Laboratory team is a significant step forward in quantum computing. It eliminates many of the problematic complexities found in current quantum computers and instead implements an algorithm in natural quantum interactions to process a variety of real-world problems faster than classical computers or conventional gate-based quantum computers can. The approach could be used to solve many practical problems proposed for quantum computers, and the team hopes to collaborate with experimental physicists to demonstrate their approach using ultracold atoms.