Motional States of Trapped Electrons as Charge Qubits
POSTER
Abstract
Superconducting charge qubits have demonstrated impressive performance across many metrics, yet their coherence times remain limited to the order of hundreds of microseconds. This limitation arises primarily from strong coupling of the qubit’s electrons to the surrounding circuit materials. In contrast, Penning traps, well‑established tools in atomic, molecular, and optical (AMO) physics, provide exceptionally stable confinement of charged particles with minimal heating, owing to their purely static electromagnetic fields and negligible power dissipation.
We propose a hybrid approach that leverages the superior isolation of Penning traps while importing the nonlinear dynamics essential for qubit operation from superconducting circuits. By deliberately deforming the trapping potential into an anharmonic configuration, the particle Hamiltonian acquires terms analogous to the Kerr nonlinearity of superconducting charge qubits. Moreover, operating the trap near the stability threshold (i.e., at very low magnetic fields where ω1=√(ωc2-2ωz2) approaches zero) dramatically enhances the self‑Kerr coefficient, providing a tunable source of anharmonicity without additional circuit elements.
Electrons or positrons serve as the quantum carriers, offering intrinsically high motional frequencies that translate into fast gate operations. A variety of cooling techniques, ranging from passive resistive and cavity cooling to RF‑based schemes, can be employed to prepare the particle in its motional ground state, further suppressing decoherence pathways.
We present preliminary proof‑of‑concept measurements that validate the feasibility of this scheme, alongside the current status of the finalized trap design. Our results indicate that Penning‑trap‑based charge qubits can achieve coherence times surpassing those of conventional superconducting devices while retaining the rapid control afforded by high motional frequencies, opening a promising new avenue for scalable quantum information processing.
We propose a hybrid approach that leverages the superior isolation of Penning traps while importing the nonlinear dynamics essential for qubit operation from superconducting circuits. By deliberately deforming the trapping potential into an anharmonic configuration, the particle Hamiltonian acquires terms analogous to the Kerr nonlinearity of superconducting charge qubits. Moreover, operating the trap near the stability threshold (i.e., at very low magnetic fields where ω1=√(ωc2-2ωz2) approaches zero) dramatically enhances the self‑Kerr coefficient, providing a tunable source of anharmonicity without additional circuit elements.
Electrons or positrons serve as the quantum carriers, offering intrinsically high motional frequencies that translate into fast gate operations. A variety of cooling techniques, ranging from passive resistive and cavity cooling to RF‑based schemes, can be employed to prepare the particle in its motional ground state, further suppressing decoherence pathways.
We present preliminary proof‑of‑concept measurements that validate the feasibility of this scheme, alongside the current status of the finalized trap design. Our results indicate that Penning‑trap‑based charge qubits can achieve coherence times surpassing those of conventional superconducting devices while retaining the rapid control afforded by high motional frequencies, opening a promising new avenue for scalable quantum information processing.
*We acknowledge the funding support of the Japan Science and Technology Agency's ASPIRE programme.
Presenters
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Markus Fleck
- RIKEN Center for Quantum Computing