Publications by Amir Youssefi | EPFL Graph Search

Compact Superconducting Vacuum-gap Capacitors with Low Microwave Loss and High Mechanical Coherence for Scalable Quantum Circuits

Tobias Kippenberg, Amir Youssefi, Marco Scigliuzzo, Mahdi Chegnizadeh

Vacuum-gap capacitors have recently attracted significant interest in superconducting circuit platforms due to their compact design and exceptionally low dielectric losses in the microwave regime. Their intrinsic ability to support mechanical vibrational m ...

American Physical Society (APS)2025

Quantum collective motion of macroscopic mechanical oscillators

Tobias Kippenberg, Amir Youssefi, Marco Scigliuzzo, Mahdi Chegnizadeh, Shingo Kono

Collective phenomena arise from interactions within complex systems, leading to behaviors absent in individual components. Observing quantum collective phenomena with macroscopic mechanical oscillators has been impeded by the stringent requirement that osc ...

American Association for the Advancement of Science2024

Ultra-high quantum coherent and scalable superconducting circuit optomechanics, from topological lattices to quantum storage

Amir Youssefi

Mechanical oscillators can exhibit modes with ultra-low energy dissipation and compact form factors due to the slow velocity of acoustic waves, and are already used in applications ranging from timing to wireless filters. Over the past decade, novel ways i ...

EPFL2024

Mechanically induced correlated errors on superconducting qubits with relaxation times exceeding 0.4 ms

Tobias Kippenberg, Amir Youssefi, Marco Scigliuzzo, Mahdi Chegnizadeh, Shingo Kono, Xuxin Wang

Superconducting qubits are among the most advanced candidates for achieving fault-tolerant quantum computing. Despite recent significant advancements in the qubit lifetimes, the origin of the loss mechanism for state-of-the-art qubits is still subject to i ...

Nature Portfolio2024

A squeezed mechanical oscillator with millisecond quantum decoherence

Tobias Kippenberg, Amir Youssefi, Mahdi Chegnizadeh, Shingo Kono

An enduring challenge in constructing mechanical-oscillator-based hybrid quantum systems is to ensure engineered coupling to an auxiliary degree of freedom and maintain good mechanical isolation from the environment, that is, low quantum decoherence, consi ...

NATURE PORTFOLIO2023

Topological lattices realized in superconducting circuit optomechanics

Tobias Kippenberg, Amir Youssefi, Mahdi Chegnizadeh, Andrea Bancora, Shingo Kono, Tatiana Vovk

Cavity optomechanics enables the control of mechanical motion through the radiation-pressure interaction(1), and has contributed to the quantum control of engineered mechanical systems ranging from kilogramme-scale Laser Interferometer Gravitational-wave O ...

NATURE PORTFOLIO2022

A cryogenic electro-optic interconnect for superconducting devices

Tobias Kippenberg, Amir Youssefi, Anton Lukashchuk, Nathan Rafaël Bernier, Liu Qiu, Itay Shomroni

A major challenge to the scalability of cryogenic computing platforms is the heat load associated with the growing number of electrical cable connections between the superconducting circuitry and the room-temperature environment. Compared with electrical c ...

2021

Automated wide-ranged finely tunable microwave cavity for narrowband phase noise filtering

Tobias Kippenberg, Amir Youssefi, Nick Jacob Sauerwein

Narrowband microwave filters have wide ranging applications, including the reduction in phase noise of microwave sources within a given frequency band. The prospect of developing an automated filter that tunes itself to an arbitrary desired frequency at ma ...

AMER INST PHYSICS2021

Two-Tone Optomechanical Instability and Its Fundamental Implications for Backaction-Evading Measurements

Tobias Kippenberg, Amir Youssefi, Liu Qiu, Itay Shomroni

While quantum mechanics imposes a fundamental limit on the precision of interferometric measurementsof mechanical motion due to measurement backaction, the nonlinear nature of the coupling also leads toparametric instabilities that place practical limits o ...

American Physical Society2019