Quantum Computing with Transmon Qubits

Michele Vischi, Luca Ferialdi, Andrea Trombettoni +1 more

The Continuous Spontaneous Localization (CSL) model is an alternative formulation of quantum mechanics which introduces a noise coupled non linearly to the wave function to account for its collapse. We consider CSL effects on quantum computers made of superconducting transmon qubits. As a direct effect CSL reduces quantum superpositions of the computational basis states of the qubits: we show the reduction rate to be negligibly small. However, an indirect effect of CSL, dissipation induced by the noise, also leads transmon qubits to decohere, by generating additional quasiparticles. Since the decoherence rate of transmon qubits depends on the quasiparticle density, by computing their generation rate induced by CSL, we can estimate the corresponding quasiparticle density and thus the limit set by CSL on the performances of transmon quantum computers. We show that CSL could spoil the quantum computation of practical algorithms on large devices. We further explore the possibility of testing CSL effects on superconducting devices.

Shay Hacohen-Gourgy, Vinay Ramasesh, Oliver Viehmann +3 more

Michele Vischi, Luca Ferialdi, Andrea Trombettoni +1 more

The continuous spontaneous localization (CSL) model is an alternative formulation of quantum mechanics, which introduces a noise-coupled nonlinearly to the wave function to account for its collapse. We consider CSL effects on quantum computers made of superconducting transmon qubits. As a direct effect CSL reduces quantum superpositions of the computational basis states of the qubits: we show the reduction rate to be negligibly small. However, an indirect effect of CSL, dissipation induced by the noise, also leads transmon qubits to decohere, by generating additional quasiparticles. Since the decoherence rate of transmon qubits depends on the quasiparticle density, by computing their generation rate induced by CSL, we can estimate the corresponding quasiparticle density and thus the limit set by CSL on the performances of transmon quantum computers. We show that CSL could spoil the quantum computation of practical algorithms on large devices. We further explore the possibility of testing CSL effects on superconducting devices.

Samuel L. Braunstein, Arun Kumar Pati

Chon‐Fai Kam, En-Jui Kuo

Abstract Transmon qubits have traditionally been regarded as limited to random circuit sampling, incapable of performing Fock state boson sampling—a problem known to be classically intractable. This work challenges that assumption by introducing q -boson Fock state sampling, a variant in which transmon qubits can operate effectively. Through direct mapping to the q -boson formalism, we demonstrate that transmons possess the capability to achieve quantum supremacy in q -boson sampling tasks. This finding expands the potential applications of transmon-based quantum processors and paves the way for new avenues in quantum computation.

Michael Hatridge, Shyam Shankar, Flavius Schackert +7 more