Researchers at University of Maryland and the Duke University have managed to present the first implementation of Fault-Tolerant (FT) logical state preparation.
They have experimentally demonstrated fault-tolerant preparation, rotation, error syndrome extraction, and measurement on a logical qubit encoded in the 9-qubit Bacon-Shor code.
The quantum computer used consists of laser cooled 171Yb+ ions trapped above a micro-fabricated chip in a room-temperature vacuum chamber.
For the logical qubit, they have measured an average fault-tolerant preparation and measurement error of 0.6% and a transversal Clifford gate with an error of 0.3% after error correction.
Remarkably, the encoding outperformed the limiting physical operation, which, in their system, is the two-qubit entangling operation. They integrated the encoded logical qubit with FT stabilizer measurement, FT logical gates, and FT measurement to achieve a code capable of correcting errors along all axes.
The paper can be read there.