First-ever teleportation of logical qubit using fault-tolerant methods

A team of engineers and physicists at quantum computing company Quantinuum has conducted the first-ever teleportation of a logical qubit using fault-tolerant methods. In their paper published in the journal Science, the group describes the setup and teleportation methods they used and the fidelity achieved by each.

One of the major sticking points in the development of a truly usable quantum computer has been the tendency of quantum computers to produce errors while working on solutions. One approach to reducing errors is the introduction of logical qubits, which can be leveraged across multiple physical qubits.

In this new effort, the research team worked with their H2 trapped-ion quantum processor, which allows for transmitting quantum encoded data using entangled physical qubits.

The reason that logical qubits can be less error prone than physical qubits is they are not susceptible to noise and they can be encoded using error-correcting code. The challenge of using logical qubits is teleporting information using quantum entanglement. To achieve their result, the researchers at Quantinuum tried two methods: transversal and lattice surgery.

The transversal approach involved adding operations to more than one qubit at the same time. This allowed for manipulating the process, which in turn led to a faster teleportation. The lattice surgery approach involved manipulating the boundaries of the qubits as a way to perform operations—it is preferable when attempting to make procedures more compatible between architectures.

The researchers found that either approach was viable as a means of transporting logical qubits, but they also had their drawbacks. The lattice surgery approach proved to have less fidelity than the transversal approach, for example.

In either case, the research team used real-time decoding (using the Steane code) as a means for applying error correction at four points along the teleportation process, achieving the first demonstration of teleportation of logical qubits using fault-tolerant methods.

The work by the team at Quantinuum represents yet another important step toward the development of a true quantum computer.

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