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Superconducting circuit with charge-parity protection: Experiment

Clarke Smith, Angela Kou, Xu Xiao +6 more

Bulletin of the American Physical SocietyMar 7, 20180 citations

Detection and manipulation of Majorana fermions in circuit QED

Clemens Müller, Jérôme Bourassa, Alexandre Blais

Motivated by recent experimental progress towards the measurement and manipulation of Majorana fermions with superconducting circuits, we propose a device interfacing Majorana fermions with circuit quantum electrodynamics. The proposed circuit acts as a charge parity detector changing the resonance frequency of a superconducting $\ensuremath{\lambda}/4$ resonator conditioned on the parity of charges on nearby gates. Operating at both charge and flux sweet spots, this device is highly insensitive to environmental noise. It enables high-fidelity single-shot quantum nondemolition readout of the state of a pair of Majorana fermions encoding a topologically protected qubit. Additionally, the interaction permits the realization of an arbitrary phase gate on the topological qubit, closing the loop for computational completeness. Away from the charge sweet spot, this device can be used as a highly sensitive charge detector with a sensitivity better than ${10}^{\ensuremath{-}4}\text{e}/\sqrt{\text{Hz}}$ and bandwidth larger than 1 MHz.Motivated by recent experimental progress towards the measurement and manipulation of Majorana fermions with superconducting circuits, we propose a device interfacing Majorana fermions with circuit quantum electrodynamics. The proposed circuit acts as a charge parity detector changing the resonance frequency of a superconducting $\ensuremath{\lambda}/4$ resonator conditioned on the parity of charges on nearby gates. Operating at both charge and flux sweet spots, this device is highly insensitive to environmental noise. It enables high-fidelity single-shot quantum nondemolition readout of the state of a pair of Majorana fermions encoding a topologically protected qubit. Additionally, the interaction permits the realization of an arbitrary phase gate on the topological qubit, closing the loop for computational completeness. Away from the charge sweet spot, this device can be used as a highly sensitive charge detector with a sensitivity better than ${10}^{\ensuremath{-}4}\text{e}/\sqrt{\text{Hz}}$ and bandwidth larger than 1 MHz.

arXiv:1306.1539Physical Review BDec 2, 201337 citations

A New Nonlinearity for Superconducting Circuits

Marric Stephens

PhysicsSep 5, 20240 citations

Design and quantization of superconducting circuits

Zlatko Minev, Thomas McConkey, Firat Solgun +3 more

Bulletin of the American Physical SocietyMar 6, 20200 citations

Parity-spin superconducting qubit based on topological insulators

Guo-Liang Guo, Han-Bing Leng, Xin Liu

Abstract We propose to utilize two parity-protected qubits which are built based on superconductor/topological-insulator/superconductor (SC/TI/SC) Josephson junction to implement a parity-spin superconducting qubit. The SC/TI/SC Josephson junctions have identical Josephson potential, which is robust against fabrication variations and guarantees the reliable cos ⁡ 2 ϕ energy-phase relation for implementing a parity-protected qubit. By viewing the even and odd parity ground states of a single parity-protected qubit as spin- 1 2 states, we construct the logic qubit states using the total parity odd subspace of two parity-protected qubits, refereed to parity-spin qubit. This parity-spin qubit exhibits robustness against charge noise, similar to a singlet-triplet (S-T) qubit’s immunity to global magnetic field fluctuations. Meanwhile, the flux noise cannot directly couple two states with the same total parity and is significantly suppressed. Benefiting from the simultaneous protection from charge and flux noise, we demonstrate an enhancement of both T 1 and T 2 coherence times. Our work presents a TI-based approach to engineer symmetry-protected superconducting qubits.Abstract We propose to utilize two parity-protected qubits which are built based on superconductor/topological-insulator/superconductor (SC/TI/SC) Josephson junction to implement a parity-spin superconducting qubit. The SC/TI/SC Josephson junctions have identical Josephson potential, which is robust against fabrication variations and guarantees the reliable cos ⁡ 2 ϕ energy-phase relation for implementing a parity-protected qubit. By viewing the even and odd parity ground states of a single parity-protected qubit as spin- 1 2 states, we construct the logic qubit states using the total parity odd subspace of two parity-protected qubits, refereed to parity-spin qubit. This parity-spin qubit exhibits robustness against charge noise, similar to a singlet-triplet (S-T) qubit’s immunity to global magnetic field fluctuations. Meanwhile, the flux noise cannot directly couple two states with the same total parity and is significantly suppressed. Benefiting from the simultaneous protection from charge and flux noise, we demonstrate an enhancement of both T 1 and T 2 coherence times. Our work presents a TI-based approach to engineer symmetry-protected superconducting qubits.

arXiv:2308.12027New Journal of PhysicsMay 14, 20242 citations

Introduction to Superconducting Quantum Circuits

Michael Stern

Lecture notes in physicsJan 1, 20240 citations

Superconducting circuit with charge-parity protection: Theory

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