Quantum-based electronics is a rapidly accelerating technology, where information is encoded in the quantum mechanical states of coupled natural or artificial atoms. The emerging quantum computers promise to address previously unsolvable computational tasks that are highly relevant to a wide range of fundamental and applied fields. To unlock the exceptional potential of quantum computers, one of the key challenges that the field has to overcome is to preserve the coherence of a quantum superposition over extended times. Besides implementing quantum error correction schemes, a complementary approach to prolong the coherence of quantum processors is to develop qubits that are intrinsically protected against decoherence. In this talk, we describe an experimental realization of the error-protected superconducting 0-π qubit [1,2,3]: an artificial atom which hosts protected states suitable for quantum-information processing. Due to the multiple degrees of freedom of the 0-π circuit, the qubit states are simultaneously immune against energy relaxation and pure dephasing due to charge- and flux-noise. Our multi-tone spectroscopy measurements reveal the energy level structure of the system, and we show that the logical qubit is encoded in quantum states with wavefunctions characterized by disjoint support and robust energies. The parity symmetry of the qubit results in charge-insensitive levels connecting the protected states, allowing for logical operations using Raman-type transitions. The measured relaxation (1.6 ms) and dephasing (25 μs) times demonstrate that our implementation of the 0-π circuit not only broadens the family of superconducting qubits but also represents a promising candidate for the building block of a fault-tolerant quantum computer.
Location - Other
Andras Gyenis / Princeton University
Electrical, Computer and Energy Engineering
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