New quantum computing paradigm: Game-changing hardware for faster computation

The quantum computing strategy uses a simple magnetic field to spin qubits, such as the spin of an electron, in a natural quantum system.

Using natural quantum interactions enables faster, more powerful calculations for Grover’s algorithm and many others.

Los Alamos National Laboratory scientists have developed a groundbreaking method Quantum Computation method using natural quantum interactions. This method promises longer-lived qubits, efficient problem solving using Grover’s algorithm, and significant error resilience.

A potentially game-changing theoretical approach to quantum computing hardware would avoid much of the problematic complexity commonly found in current quantum computers. This strategy deploys an algorithm in natural quantum interactions to handle many real-world problems faster than classical computers or conventional gate-based quantum computers can.

“Our discovery eliminates many of the challenging requirements for quantum hardware,” said Nikolai Sinitsyn, a theoretical physicist at Los Alamos National Laboratory. He co-authored a paper on this approach published August 14 in the journal Physical assessment A. “Natural systems, such as the electron spins of defects in diamond, have the exact type of interactions that are essential for our calculations.”

Sinitsyn said the team hopes to collaborate with experimental physicists also at Los Alamos to demonstrate their method using ultracold atoms. Modern technologies in supercold atoms are advanced enough to demonstrate such calculations with about 40 to 60 qubits, he said, enough to solve many problems currently inaccessible to classical computing. or binary. A qubit is the basic unit of quantum information, similar to the familiar bit in classical computing.

Qubits last longer

Instead of setting up a complex system of logic gates between several qubits that must all share quantum entanglement, the new strategy uses a simple magnetic field to rotate the qubits, such as the spin of an electron, in a system. natural system. The precise evolution of the spin states is all that is needed to implement the algorithm. Sinitsyn said the method could be used to solve many practical problems proposed for quantum computers.

Quantum computing is still a nascent field limited by the difficulty of connecting qubits in long chains of logic gates and maintaining the quantum entanglement required for computation. Entanglement breaks down in a process called decoherence, when entangled qubits begin to interact with the world outside the computer’s quantum system, causing errors. That happens quickly, limiting computation time. True error correction has yet to be implemented on quantum hardware.

The new approach relies on natural entanglement instead of induction, so it requires fewer connections between qubits. That reduces the impact of incoherence. Therefore, the qubits last relatively long, Sinitsyn said.

Advances in quantum algorithms

The Los Alamos team’s theoretical paper shows that this approach can solve the number division problem using Grover’s algorithm faster than existing quantum computers. As one of the most famous quantum algorithms, it allows unstructured search of large data sets that consume conventional computing resources. For example, Sinitsyn said, Grover’s algorithm could be used to divide the running time of tasks equally between two computers, so that they complete at the same time, along with other actual work. This algorithm is well suited to idealized, error-correcting quantum computers, although it is difficult to implement on today’s error-prone machines.

Error recovery and simplicity

Quantum computers are built to perform calculations much faster than any classical device can, but until now they have been extremely difficult to do, Sinitsyn said. A typical quantum computer implements quantum circuits – sequences of basic operations with different pairs of qubits.

Los Alamos theorists have proposed an intriguing alternative.

“We found that for many well-known computational problems, it is enough to have a quantum system with fundamental interactions, in which just a single quantum spin – is possible,” said Sinitsyn. obtained by two qubits – interacting with the rest of the computational qubits”. “Then, a single magnetic pulse acting only on the central spin performs the most complex part of the quantum Grover algorithm.” Known as Grover’s prophecy, this quantum activity points to the desired solution.

“There is no need for direct interactions between the computational qubits and no need for time-dependent interactions with the central spin in this process,” he said. Once the static couplings between the central spin and the qubit are established, he says, the entire computation consists of simply applying time-dependent external field pulses to spin the spins.

Importantly, the team demonstrated that such operations can be carried out quickly. The team also found that their approach was structurally defensible. That is, it is resistant to many errors in the precision of the control field and other physical parameters even without correcting quantum errors.

Reference: “Topology-Protected Grover’s Prophecy for the Partition Problem” by Nikolai A. Sinitsyn and Bin Yan, August 14, 2023, Physical assessment A.
DOI: 10.1103/PhysRevA.108.022412

Funding: Department of Energy Office of Science, Office of Advanced Scientific Computing Research, and Laboratory Directed Research and Development Program at Los Alamos National Laboratory.