Schrödinger cat states of a 16-microgram mechanical oscillator

Bild, Marius; Fadel, Matteo; Yang, Yu; Lüpke, Uwe von; Martin, Phillip; Bruno, Alessandro; Chu, Yiwen

doi:10.1126/science.adf7553

Cited by 62 publications

(12 citation statements)

References 46 publications

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“…Although the cQAD device used in this work has been previously studied in both dispersive 5 and resonant coupling regimes 6 , here we focus on direct multimode interactions that arise when two parametric drives are applied to the qubit. The Hamiltonian of our system in the presence of these drives is given by where we assume g m to be real.…”

Section: Mainmentioning

confidence: 99%

Engineering multimode interactions in circuit quantum acoustodynamics

von Lüpke,

Rodrigues,

Yang

et al. 2024

Nat. Phys.

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In recent years, important progress has been made towards encoding and processing quantum information in the large Hilbert space of bosonic modes. Mechanical resonators have several practical advantages for this purpose, because they confine many high-quality-factor modes into a small volume and can be easily integrated with different quantum systems. However, it is challenging to create direct interactions between different mechanical modes that can be used to emulate quantum gates. Here we demonstrate an in situ tunable beamsplitter-type interaction between several mechanical modes of a high-overtone bulk acoustic-wave resonator. The engineered interaction is mediated by a parametrically driven superconducting transmon qubit, and we show that it can be tailored to couple pairs or triplets of phononic modes. Furthermore, we use this interaction to demonstrate the Hong–Ou–Mandel effect between phonons. Our results lay the foundations for using phononic systems as quantum memories and platforms for quantum simulations.

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Section: Mainmentioning

confidence: 99%

Engineering multimode interactions in circuit quantum acoustodynamics

von Lüpke,

Rodrigues,

Yang

et al. 2024

Nat. Phys.

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“…al. [45] but use updated parameters. In this experiment, the phonon mode we couple to is not strictly an eigenmode of the system, but is instead formed by a superposition of eigenmodes.…”

Section: K Effective Massmentioning

confidence: 99%

Brillouin optomechanics in the quantum ground state

Doeleman¹,

Schatteburg²,

Benevides³

et al. 2023

Preprint

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Bulk acoustic wave (BAW) resonators are attractive as intermediaries in a microwave-to-optical transducer, due to their long coherence times and controllable coupling to optical photons and superconducting qubits. However, for an optomechanical transducer to operate without detrimental added noise, the mechanical modes must be in the quantum ground state. This has proven challenging in recent demonstrations of transduction based on other types of mechanical resonators, where absorption of laser light caused heating of the phonon modes. In this work, we demonstrate ground state operation of a Brillouin optomechanical system composed of a quartz BAW resonator inside an optical cavity. The system is operated at ∼200 mK temperatures inside a dilution refrigerator, which is made possible by designing the system so that it self-aligns during cooldown and is relatively insensitive to mechanical vibrations. We show optomechanical coupling to several phonon modes and perform sideband asymmetry thermometry to demonstrate a thermal occupation below 0.5 phonons at base temperature. This constitutes the heaviest (∼ 494 µg) mechanical object measured in the quantum ground state to date. Further measurements confirm a negligible effect of laser heating on this phonon occupation. Our results pave the way toward low-noise, high-efficiency microwave-to-optical transduction based on BAW resonators.

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“…This is because the quantum of these collective excitations (magnon) is capable of coupling many different systems, including optical photons [8][9][10][11], microwave photons [12][13][14][15][16][17], phonons [18][19][20][21], and superconducting qubits [22][23][24][25][26]. More importantly, the large size of the ferromagnetic spin system (∼1 mm) and the enormous number of spins in it (∼10 19 ) also make it an ideal platform for testing some fundamental properties in quantum mechanics, such as the quantum entanglement between macroscopic systems [27][28][29][30][31][32][33][34][35]. Indeed, quantum entanglement between macroscopic objects containing a very large number of atoms is of particular importance and has been demonstrated in various systems, such as the circuit QED system [36] and the mechanical resonator [37].…”

Section: Introductionmentioning

confidence: 99%

Macroscopic Bell state between a millimeter-sized spin system and a superconducting qubit

Xu,

Gu,

Weng

et al. 2024

Quantum Sci. Technol.

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Entanglement is a fundamental property in quantum mechanics that systems share inseparable quantum correlation regardless of their mutual distances. Owing to the fundamental significance and versatile applications, the generation of quantum entanglement between macroscopic systems has been a focus of current research. Here we report on the deterministic generation and tomography of the macroscopically entangled Bell state in a hybrid quantum system containing a millimeter-sized spin system ($\sim 1\times10^{19}$ atoms) and a micrometer-sized superconducting qubit. The deterministic generation is realized by coupling the macroscopic spin system and the qubit via a microwave cavity. Also, we develop a joint tomography approach to confirming the deterministic generation of the Bell state, which gives a generation fidelity of $0.90\pm0.01$. Our work makes the macroscopic spin system the largest system (in the sense of atom number) capable of generating the maximally entangled quantum state.

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Schrödinger cat states of a 16-microgram mechanical oscillator

Cited by 62 publications

References 46 publications

Engineering multimode interactions in circuit quantum acoustodynamics

Engineering multimode interactions in circuit quantum acoustodynamics

Brillouin optomechanics in the quantum ground state

Macroscopic Bell state between a millimeter-sized spin system and a superconducting qubit

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