Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session M67: Hybrid Quantum Systems IFocus
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Sponsoring Units: DQI Chair: Junho Suh, Korea Research Inst of Standards and Science Room: Room 412 |
Wednesday, March 8, 2023 8:00AM - 8:12AM |
M67.00001: A squeezed mechanical oscillator with milli-second quantum decoherence Mahdi Chegnizadeh, Amir Youssefi, Shingo Kono, Tobias J Kippenberg The development of mechanical oscillator-based hybrid quantum systems has allowed quantum state preparation and measurements of macroscopic mechanical systems. These systems need to satisfy the dichotomy of engineered coupling to an auxiliary degree of freedom, while being mechanically well isolated from the environment, which induces both thermal decoherence and dephasing. Here we demonstrate a micro-mechanical oscillator coupled to a superconducting microwave circuit with a thermal decoherence rate of only 20.5 Hz (130 quanta/second motional heating rate) and a dephasing rate of 0.09 Hz - on par with and better than, respectively, what has been achieved with trapped ions. This allows us to directly track the free evolution of a squeezed mechanical state over milli-second timescales. Such ultra-low quantum decoherence not only increases the fidelity of quantum control over macroscopic mechanical systems, but may equally benefit mechanical oscillator-based schemes for quantum computing and transduction, fundamental tests of quantum mechanics itself, or searches for dark matter. |
Wednesday, March 8, 2023 8:12AM - 8:24AM |
M67.00002: Optically heralded microwave photons - Part 1 Felix M Mayor, Wentao Jiang, Sultan Malik, Raphael Van Laer, Timothy P McKenna, Rishi N Patel, Jeremy D Witmer, Amir H Safavi-Naeini Future quantum networks of distant superconducting microwave quantum processors demand the use of optical photons for low loss and low noise interconnects. Bridging the energy gap between microwave and optical photons, however, requires the use of a frequency converter. Here, we demonstrate a frequency converter that can add a single photon to the microwave field conditioned on the detection of an optical photon. The device consists of a hybrid lithium niobate - silicon gigahertz nanomechanical resonator acting as an intermediary between a microwave and optical channel via strong piezoelectric and optomechanical interactions. For pulsed microwave photon generation, we achieve a heralding rate of 15 Hz. Thermal noise added by optical absorption in the device amounts to less than 2 microwave photons. Additionally, we measure a microwave-to-optical conversion efficiency of 5% under continuous wave operation. Finally, we discuss necessary steps for increasing the heralding rate and reducing thermal noise. Improving the device performance and system efficiency should pave the way for entangling two distant microwave-frequency quantum nodes through joint measurement on optical photons from a pair of transducers. |
Wednesday, March 8, 2023 8:24AM - 8:36AM |
M67.00003: Optically heralded microwave photons - Part 2 Sultan Malik, Wentao Jiang, Felix M Mayor, Raphael Van Laer, Timothy P McKenna, Rishi N Patel, Jeremy D Witmer, Amir H Safavi-Naeini Integrated piezo-optomechanical systems are a promising platform for microwave-to-optical quantum frequency conversion. Because of the inherent impedance mismatch between the nanoscale GHz mechanical mode and microwave transmission line, an intermediary microwave resonance is utilized to enhance the external coupling rate. The microwave resonances are formed by the standing waves in a high-impedance (high-Z) superconducting waveguide on a niobium-titanium-nitride (NbTiN) platform. To simplify fabrication and minimize optically induced quasiparticle generation, the piezo-optomechanical element and the microwave circuit are fabricated on separate chips and heterogeneously integrated via cross-chip wirebonds. The large kinetic inductance from NbTiN nanowires enables magnetic frequency tunability allowing us to bring one microwave mode in resonance with the mechanical mode, enhancing the conversion efficiency. Beyond the quantum frequency conversion application, such a high-Z waveguide provides a convenient and flexible way of enhancing the external coupling rate of various piezo-electric nanomechanical systems. |
Wednesday, March 8, 2023 8:36AM - 8:48AM |
M67.00004: Electrostatic coupling of microwave photons and phonons in a silicon phononic crystal resonator Alkim Bozkurt, Han Zhao, Chaitali Joshi, Henry G LeDuc, Peter K Day, Mohammad Mirhosseini Mechanical oscillators with long energy relaxation lifetimes possess significant potential for quantum information processing, in the form of quantum memories and transducers. We present the design and measurement of an electromechanical system, which generates interactions between resonant GHz frequency microwave photons and acoustic phonons on a silicon-on-insulator platform. The system is based on electrostatic transduction, where the application of an external electric field on a moving capacitor engenders an electromechanical interaction. Bandgap engineering of the phononic crystal resonator combined with the avoidance of lossy piezoelectric materials gives rise to significant phonon lifetimes, reaching 265μs (Q ∼ 10 million at 5GHz). A tunable high impedance TiN microwave resonator ensures the resonance condition while simultaneously boosting the electromechanical interaction, which can be parametrically enhanced to reach g/2π = 1.1MHz, sufficient for the system to enter the strong coupling regime. Mode thermometry measurements conducted at mK temperatures indicate the absence of any significant drive induced heating, despite the large electric fields applied to the device, with both mechanical and microwave resonators remaining in their ground state. The combination of long lifetime, large coupling strength and ground state operation establishes our system in a favorable position for future quantum acoustics and transduction experiments. |
Wednesday, March 8, 2023 8:48AM - 9:00AM |
M67.00005: Quantum memory unit with high-Q nanomechanical resonator YANG HU, Angad Gupta, Michael J Hatridge, Thomas Purdy Hybrid quantum systems integrating mechanical resonators with superconducting qubits are promising quantum information platforms. Mechanical modes with high quality factor and small mode volume will serve as a great quantum memory unit to store qubit information with the advantage of long lifetime and small size. We present phononic crystal quartz resonators and surface acoustic wave quartz resonators with mechanical modes of high quality factor and small mode volume. The modes of both mechanical resonators are around 200MHz and will parametrically couple to GHz-frequency superconducting qubits with the assistance of a nonlinear circuit element (SNAIL) to mediate their frequency mismatch, based on three-wave mixing mechanics. The quartz resonators and SNAIL are on different chips which will be bonded in a flip-chip method and coupled via piezoelectric effect. Such modularity will also improve the flexibility and scalability of the hybrid system integration. |
Wednesday, March 8, 2023 9:00AM - 9:12AM |
M67.00006: Schrödinger cat states of a 16μg mechanical oscillator: Part I Yu Yang While the validity of superposition principle is routinely validated for microscopic systems, it is still unclear why we do not observe macroscopic objects to be in superpositions of states that can be distinguished by some classical property. In our experiments, we demonstrate the preparation of a mechanical resonator with an effective mass of 16ug in Schrodinger cat states of motion, where the constituent atoms oscillate in a superposition of two opposite phases. This first talk describes the bulk acoustic wave resonator device used in our experiments and the circuit quantum acoustodynamics (cQAD) toolbox we have developed. By using the resonant Jaynes-Cummings interaction between the resonator mode and a superconducting qubit, we are able to demonstrate the evolution of an initial mechanical coherent state into a Schrödinger cat state. |
Wednesday, March 8, 2023 9:12AM - 9:24AM |
M67.00007: Schrödinger cat state of a 16μg mechanical oscillator: Part II Matteo Fadel While the validity of superposition principle is routinely validated for microscopic systems, it is still unclear why we do not observe macroscopic objects to be in superpositions of states that can be distinguished by some classical property. In our experiments we demonstrate the preparation of a mechanical resonator with an effective mass of 16ug in Schrodinger cat states of motion, where the constituent atoms oscillate in a superposition of two opposite phases. This second talk presents experimental results on the preparation of a bulk acoustic wave resonator in Schrödinger cat states with different amplitudes and phases. Moreover, we investigate the decoherence dynamics of such states by observing the disappearance of Wigner negativities. Our results can find applications in continuous variable quantum information processing and in fundamental investigations of quantum mechanics in massive systems. |
Wednesday, March 8, 2023 9:24AM - 9:36AM |
M67.00008: Phonon-polaritons in the deep-strong coupling regime Andrey Baydin, Manukumara Manjappa, Sobhan Subhra Mishra, Hongjing Xu, Fuyang Tay, Dasom Kim, Felix G Hernandez, Paulo Rappl, Eduardo Abramof, Ranjan Singh, Junichiro Kono Formation of polaritons in the ultrastrong and deep-strong (DSC) coupling regimes provides opportunities for exploring novel phases of light–matter hybrids as well as for applications in quantum information processing and technology. Phonon-polaritons are particularly interesting as they are expected to be able to modify and control chemical reactions and superconductivity; they are also predicted to induce a new type of ferroelectric phase transitions. Here, we investigate coupling between vacuum photons and phonons in lead telluride in small-mode-volume terahertz cavities. Using metamaterial cavities to enhance vacuum fluctuation fields in the terahertz range, we observed a Rabi splitting whose value exceeded the cavity-phonon frequency, placing us in the DSC regime. We systematically studied the coupling strength as a function of sample thickness, temperature, and cavity length. These experimental results will be discussed in comparison with results of electromagnetic simulations we conducted. |
Wednesday, March 8, 2023 9:36AM - 10:12AM |
M67.00009: Quantum Optomechanics with Superfluid Helium Invited Speaker: Yogesh Patil I will describe our work using single photon detectors to probe the motional states of a superfluid He-4 resonator of mass ∼ 1 ng [1]. The arrival times of Stokes and anti-Stokes photons (scattered by the resonator’s acoustic mode) are used to measure the resonator’s phonon coherences up to the fourth order, when it is initialized in a thermal state of mean phonon occupancy nth∼1. The measurement backaction of such single photon detection is the heralded creation (or annihilation) of phonons in the mechanical mode. So, by postselecting on these detection events, we also measure the phonon coherences of the resonator when ≤ 3 phonons have been added or subtracted to the thermal state. Coherences and other statistics of k-quanta -subtracted or -added states of light are of interest in quantum metrology, quantum information, and quantum thermodynamics, and this work extends the potential use of such states to optomechanical platforms. |
Wednesday, March 8, 2023 10:12AM - 10:24AM |
M67.00010: Ultracoherent diamond nanomechanical resonators protected by a phononic bandgap Xinzhu Li, Ignas Lekavicius, Hailin Wang Ultracoherent nanomechanical resonators are essential components in optomechanics, spin-mechanics and phonon-mediated hybrid quantum systems. In silicon and silicon-nitride based systems, phononic bandgap structures have been proven effective in protecting a mechanical mode from coupling to its surrounding environment. Here we present the design, fabrication and characterization of diamond-based nanomechanical resonators embedded in a square phononic crystal lattice with mechanical Q-factors exceeding 10^6 at frequencies as high as 100MHz for out-of-plane modes. We show that the robust protection from a phononic bandgap can lead to a three-orders-of-magnitude increase in the mechanical quality factors. The ultracoherent mechanical modes can be coupled to color centers that feature excellent spin and optical properties, leading to a promising hybrid quantum system for pursuing spin-phonon coupling studies. |
Wednesday, March 8, 2023 10:24AM - 10:36AM |
M67.00011: Mechanical frequency control in inductively coupled electromechanical systems Thomas Luschmann, Philip E Schmidt, Frank Deppe, Achim Marx, Alvaro Sanchez, Rudolf Gross, Hans Huebl Nano-electromechanical systems couple mechanical motion to superconducting quantum circuits at microwave frequencies. While traditional, capacitive coupling strategies operate in the weak coupling regime, inductive coupling schemes based on partially suspended superconducting interference devices (SQUID) have demonstrated significantly improved coupling rates. Such systems are expected to allow for the exploration of phenomena beyond the linearized opto-mechanical interaction. Here, we present an investigation into the tuning of the mechanical resonance frequency in an inductively coupled system. The experimental data quantitatively corroborates theoretical predictions for SQUID-based electromechanical systems. In addition, we observe a magnetic field dependent tuning of the mechanical resonance frequency, which we attribute to an effective interaction of the atomic lattice and the superconducting vortex lattice. |
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