Microsoft Technology Licensing, LLC

David Alexander Aasen

Parsa Hassan Bonderson

Matthew Benjamin Hastings

Christina Paulsen Knapp

Zhenghan Wang

Jeongwan Haah

Roman Bela Bauer

Aspects of the disclosure include removing a faulty qubit in a quantum circuit. The faulty qubit is determined to be in the quantum circuit, the faulty qubit being associated with a plaquette having other qubits, where adjacent plaquettes are neighboring the plaquette. A route is determined to isolate the plaquette from the adjacent plaquettes. Measurements are caused to be performed on the quantum circuit for the route that isolates the plaquette having the faulty qubit and the other qubits.

Fault tolerant Hastings-Haah codes in the presence of dead qubits

A computing system including a processor configured to receive an indication of one or more dead data qubits and one or more dead auxiliary qubits among qubits included in a quantum computing device. The qubits are arranged in a lattice that includes plaquettes. Each of the plaquettes includes data qubits and auxiliary qubits. The processor is further configured to compute a reduced lattice by, for each of the plaquettes that includes at least one dead data qubit, computing a respective first reduced plaquette that omits the dead data qubit. For each of the plaquettes that includes at least one dead auxiliary qubit, the processor is further configured to compute the reduced lattice at least in part by computing a respective second reduced plaquette that omits the dead auxiliary qubit. The processor is further configured to output instructions to implement an error correction code on the reduced lattice.

Reduction of qubit lattice that includes dead data qubits and auxiliary qubits

A method and apparatus for performing quantum error correction using an automorphism code related to the honeycomb code. The automorphism code is based on Kramers-Wannier (KW) duality. For embodiments on a hexagonal lattice using three repeated time steps, ⅓ of the pixels are active in a given time steps. In a given time step r, a KW circuit is applied to plaquettes labeled r mod 3, transferring quantum information from the active qubits at the beginning to a new set of active qubits at the end of the time step. Each of the three plaquette types is associated with one stabilizer either given by a product of six Z operators or three X operators. The KW circuit maps the product of X operators to the product of Z operators and vice-versa. The stabilizer group of the superlattice toric code changes every round.

Quantum code with simpler pairwise checks

A computing system including a quantum computing device that includes Majorana islands at which Majorana zero modes (MZMs) are instantiated. The computing system further includes a controller configured to control the quantum computing device to perform a joint parity measurement at two or more MZMs. The controller is further configured to control the quantum computing device to perform quasiparticle poisoning (QPP) detection at the one or more Majorana islands to thereby generate error data. The error data includes one or more QPP indications associated with the one or more Majorana islands. The controller is further configured to receive the error data from the quantum computing device. The controller is further configured to update an accumulated error state of the one or more Majorana islands based at least in part on the error data, and to perform an update operation based at least in part on the accumulated error state.

Tracking and mitigation of quasiparticle poisoning errors in Majorana quantum computing systems

A computing system including a quantum computing device. The quantum computing device includes a Majorana island, a quantum dot (QD), an electrical ground, and a capacitance sensor. The computing system further includes a controller configured to, in each of a plurality of sampling iterations, control the quantum computing device to electrically couple the Majorana island to the electrical ground, disconnect the Majorana island from the electrical ground, electrically couple the Majorana island to the QD, scan over values of a first plunger gate voltage applied to a first plunger gate and a second plunger gate voltage applied to a second plunger gate, and output quantum capacitance measurements. The controller is further configured to receive the quantum capacitance measurements and determine a measured distribution of resonance regions associated with the sampling iterations. The controller is further configured to identify a minimum-energy resonance region and output the minimum-energy resonance region identification.

Growing community of inventors

Santa Barbara, CA, United States of America

David Alexander Aasen