@article{11417,
abstract = {Over the past few years, the field of quantum information science has seen tremendous progress toward realizing large-scale quantum computers. With demonstrations of quantum computers outperforming classical computers for a select range of problems,1–3 we have finally entered the noisy, intermediate-scale quantum (NISQ) computing era. While the quantum computers of today are technological marvels, they are not yet error corrected, and it is unclear whether any system will scale beyond a few hundred logical qubits without significant changes to architecture and control schemes. Today's quantum systems are analogous to the ENIAC (Electronic Numerical Integrator And Computer) and EDVAC (Electronic Discrete Variable Automatic Computer) systems of the 1940s, which ran on vacuum tubes. These machines were built on a solid, nominally scalable architecture and when they were developed, nobody could have predicted the development of the transistor and the impact of the resulting semiconductor industry. Simply put, the computers of today are nothing like the early computers of the 1940s. We believe that the qubits of future fault-tolerant quantum systems will look quite different from the qubits of the NISQ machines in operation today. This Special Topic issue is devoted to new and emerging quantum systems with a focus on enabling technologies that can eventually lead to the quantum analog to the transistor. We have solicited both research4–18 and perspective articles19–21 to discuss new and emerging qubit systems with a focus on novel materials, encodings, and architectures. We are proud to present a collection that touches on a wide range of technologies including superconductors,7–13,21 semiconductors,15–17,19 and individual atomic qubits.18
},
author = {Sigillito, Anthony J. and Covey, Jacob P. and Fink, Johannes M and Petersson, Karl and Preble, Stefan},
issn = {0003-6951},
journal = {Applied Physics Letters},
number = {19},
publisher = {American Institute of Physics},
title = {{Emerging qubit systems: Guest editorial}},
doi = {10.1063/5.0097339},
volume = {120},
year = {2022},
}
@article{11591,
abstract = {We investigate the deterministic generation and distribution of entanglement in large quantum networks by driving distant qubits with the output fields of a nondegenerate parametric amplifier. In this setting, the amplifier produces a continuous Gaussian two-mode squeezed state, which acts as a quantum-correlated reservoir for the qubits and relaxes them into a highly entangled steady state. Here we are interested in the maximal amount of entanglement and the optimal entanglement generation rates that can be achieved with this scheme under realistic conditions taking, in particular, the finite amplifier bandwidth, waveguide losses, and propagation delays into account. By combining exact numerical simulations of the full network with approximate analytic results, we predict the optimal working point for the amplifier and the corresponding qubit-qubit entanglement under various conditions. Our findings show that this passive conversion of Gaussian into discrete-variable entanglement offers a robust and experimentally very attractive approach for operating large optical, microwave, or hybrid quantum networks, for which efficient parametric amplifiers are currently developed.},
author = {Agustí, J. and Minoguchi, Y. and Fink, Johannes M and Rabl, P.},
issn = {2469-9934},
journal = {Physical Review A},
number = {6},
publisher = {American Physical Society},
title = {{Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams}},
doi = {10.1103/PhysRevA.105.062454},
volume = {105},
year = {2022},
}
@inproceedings{12088,
abstract = {We present a quantum-enabled microwave-telecom interface with bidirectional conversion efficiencies up to 15% and added input noise quanta as low as 0.16. Moreover, we observe evidence for electro-optic laser cooling and vacuum amplification.},
author = {Sahu, Rishabh and Hease, William J and Rueda Sanchez, Alfredo R and Arnold, Georg M and Qiu, Liu and Fink, Johannes M},
booktitle = {Conference on Lasers and Electro-Optics},
isbn = {9781557528209},
location = {San Jose, CA, United States},
publisher = {Optica Publishing Group},
title = {{Realizing a quantum-enabled interconnect between microwave and telecom light}},
doi = {10.1364/CLEO_QELS.2022.FW4D.4},
year = {2022},
}
@misc{13057,
abstract = {This dataset comprises all data shown in the figures of the submitted article "Geometric superinductance qubits: Controlling phase delocalization across a single Josephson junction". Additional raw data are available from the corresponding author on reasonable request.},
author = {Peruzzo, Matilda and Hassani, Farid and Szep, Grisha and Trioni, Andrea and Redchenko, Elena and Zemlicka, Martin and Fink, Johannes M},
publisher = {Zenodo},
title = {{Geometric superinductance qubits: Controlling phase delocalization across a single Josephson junction}},
doi = {10.5281/ZENODO.5592103},
year = {2021},
}
@article{9242,
abstract = {In the recent years important experimental advances in resonant electro-optic modulators as high-efficiency sources for coherent frequency combs and as devices for quantum information transfer have been realized, where strong optical and microwave mode coupling were achieved. These features suggest electro-optic-based devices as candidates for entangled optical frequency comb sources. In the present work, I study the generation of entangled optical frequency combs in millimeter-sized resonant electro-optic modulators. These devices profit from the experimentally proven advantages such as nearly constant optical free spectral ranges over several gigahertz, and high optical and microwave quality factors. The generation of frequency multiplexed quantum channels with spectral bandwidth in the MHz range for conservative parameter values paves the way towards novel uses in long-distance hybrid quantum networks, quantum key distribution, enhanced optical metrology, and quantum computing.},
author = {Rueda Sanchez, Alfredo R},
issn = {2469-9934},
journal = {Physical Review A},
number = {2},
publisher = {American Physical Society},
title = {{Frequency-multiplexed hybrid optical entangled source based on the Pockels effect}},
doi = {10.1103/PhysRevA.103.023708},
volume = {103},
year = {2021},
}
@misc{10644,
abstract = {The purpose of this application note is to demonstrate a working example of a superconducting qubit measurement in a Bluefors cryostat using the Keysight quantum control hardware. Our motivation is twofold. First, we provide pre-qualification data that the Bluefors cryostat, including filtering and wiring, can support long-lived qubits. Second, we demonstrate that the Keysight system (controlled using Labber) provides a straightforward solution to perform these characterization measurements. This document is intended as a brief guide for starting an experimental platform for testing superconducting qubits. The setup described here is an immediate jumping off point for a suite of applications including testing quantum logical gates, quantum optics with microwaves, or even using the qubit itself as a sensitive probe of local electromagnetic fields. Qubit measurements rely on high performance of both the physical sample environment and the measurement electronics. An overview of the cryogenic system is shown in Figure 1, and an overview of the integration between the electronics and cryostat (including wiring details) is shown in Figure 2.},
author = {Lake, Russell and Simbierowicz, Slawomir and Krantz, Philip and Hassani, Farid and Fink, Johannes M},
keywords = {Application note},
pages = {9},
publisher = {Bluefors Oy},
title = {{The Bluefors dilution refrigerator as an integrated quantum measurement system}},
year = {2021},
}
@misc{10645,
abstract = {Superconducting qubits have emerged as a highly versatile and useful platform for quantum technological applications [1]. Bluefors and Zurich Instruments have supported the growth of this field from the 2010s onwards by providing well-engineered and reliable measurement infrastructure [2]– [6]. Having a long and stable qubit lifetime is a critical system property. Therefore, considerable effort has already gone into measuring qubit energy-relaxation timescales and their fluctuations, see Refs. [7]–[10] among others. Accurately extracting the statistics of a quantum device requires users to perform time consuming measurements. One measurement challenge is that the detection of the state-dependent
response of a superconducting resonator due to a dispersively-coupled qubit requires an inherently low signal level. Consequently, measurements must be performed using a microwave probe that contains only a few microwave photons. Improving the signal-to-noise ratio (SNR) by using near-quantum limited parametric amplifiers as well as the use of optimized signal processing enabled by efficient room temperature instrumentation help to reduce measurement time. An empirical observation for fixed frequency transmons from recent literature is that as the energy-relaxation time 𝑇𝑇1 increases, so do its natural temporal fluctuations [7], [10]. This necessitates many repeated measurements to understand the statistics (see for example, Ref. [10]). In addition, as state-of-the-art qubits increase in lifetime, longer
measurement times are expected to obtain accurate statistics. As described below, the scaling of the widths of the qubit energy-relaxation distributions also reveal clues about the origin of the energy-relaxation.},
author = {Simbierowicz, Slawomir and Shi, Chunyan and Collodo, Michele and Kirste, Moritz and Hassani, Farid and Fink, Johannes M and Bylander, Jonas and Perez Lozano, Daniel and Lake, Russell},
keywords = {Application note},
pages = {8},
publisher = {Bluefors Oy},
title = {{Qubit energy-relaxation statistics in the Bluefors quantum measurement system}},
year = {2021},
}
@article{9815,
abstract = {The quantum bits (qubits) on which superconducting quantum computers are based have energy scales corresponding to photons with GHz frequencies. The energy of photons in the gigahertz domain is too low to allow transmission through the noisy room-temperature environment, where the signal would be lost in thermal noise. Optical photons, on the other hand, have much higher energies, and signals can be detected using highly efficient single-photon detectors. Transduction from microwave to optical frequencies is therefore a potential enabling technology for quantum devices. However, in such a device the optical pump can be a source of thermal noise and thus degrade the fidelity; the similarity of input microwave state to the output optical state. In order to investigate the magnitude of this effect we model the sub-Kelvin thermal behavior of an electro-optic transducer based on a lithium niobate whispering gallery mode resonator. We find that there is an optimum power level for a continuous pump, whilst pulsed operation of the pump increases the fidelity of the conversion.},
author = {Mobassem, Sonia and Lambert, Nicholas J. and Rueda Sanchez, Alfredo R and Fink, Johannes M and Leuchs, Gerd and Schwefel, Harald G.L.},
issn = {2058-9565},
journal = {Quantum Science and Technology},
number = {4},
publisher = {IOP Publishing},
title = {{Thermal noise in electro-optic devices at cryogenic temperatures}},
doi = {10.1088/2058-9565/ac0f36},
volume = {6},
year = {2021},
}
@phdthesis{9920,
abstract = {This work is concerned with two fascinating circuit quantum electrodynamics components, the Josephson junction and the geometric superinductor, and the interesting experiments that can be done by combining the two. The Josephson junction has revolutionized the field of superconducting circuits as a non-linear dissipation-less circuit element and is used in almost all superconducting qubit implementations since the 90s. On the other hand, the superinductor is a relatively new circuit element introduced as a key component of the fluxonium qubit in 2009. This is an inductor with characteristic impedance larger than the resistance quantum and self-resonance frequency in the GHz regime. The combination of these two elements can occur in two fundamental ways: in parallel and in series. When connected in parallel the two create the fluxonium qubit, a loop with large inductance and a rich energy spectrum reliant on quantum tunneling. On the other hand placing the two elements in series aids with the measurement of the IV curve of a single Josephson junction in a high impedance environment. In this limit theory predicts that the junction will behave as its dual element: the phase-slip junction. While the Josephson junction acts as a non-linear inductor the phase-slip junction has the behavior of a non-linear capacitance and can be used to measure new Josephson junction phenomena, namely Coulomb blockade of Cooper pairs and phase-locked Bloch oscillations. The latter experiment allows for a direct link between frequency and current which is an elusive connection in quantum metrology. This work introduces the geometric superinductor, a superconducting circuit element where the high inductance is due to the geometry rather than the material properties of the superconductor, realized from a highly miniaturized superconducting planar coil. These structures will be described and characterized as resonators and qubit inductors and progress towards the measurement of phase-locked Bloch oscillations will be presented.},
author = {Peruzzo, Matilda},
isbn = {978-3-99078-013-8},
issn = {2663-337X},
keywords = {quantum computing, superinductor, quantum metrology},
pages = {149},
publisher = {Institute of Science and Technology Austria},
title = {{Geometric superinductors and their applications in circuit quantum electrodynamics}},
doi = {10.15479/at:ista:9920},
year = {2021},
}
@article{9928,
abstract = {There are two elementary superconducting qubit types that derive directly from the quantum harmonic oscillator. In one, the inductor is replaced by a nonlinear Josephson junction to realize the widely used charge qubits with a compact phase variable and a discrete charge wave function. In the other, the junction is added in parallel, which gives rise to an extended phase variable, continuous wave functions, and a rich energy-level structure due to the loop topology. While the corresponding rf superconducting quantum interference device Hamiltonian was introduced as a quadratic quasi-one-dimensional potential approximation to describe the fluxonium qubit implemented with long Josephson-junction arrays, in this work we implement it directly using a linear superinductor formed by a single uninterrupted aluminum wire. We present a large variety of qubits, all stemming from the same circuit but with drastically different characteristic energy scales. This includes flux and fluxonium qubits but also the recently introduced quasicharge qubit with strongly enhanced zero-point phase fluctuations and a heavily suppressed flux dispersion. The use of a geometric inductor results in high reproducibility of the inductive energy as guaranteed by top-down lithography—a key ingredient for intrinsically protected superconducting qubits.},
author = {Peruzzo, Matilda and Hassani, Farid and Szep, Gregory and Trioni, Andrea and Redchenko, Elena and Zemlicka, Martin and Fink, Johannes M},
issn = {2691-3399},
journal = {PRX Quantum},
keywords = {quantum physics, mesoscale and nanoscale physics},
number = {4},
pages = {040341},
publisher = {American Physical Society},
title = {{Geometric superinductance qubits: Controlling phase delocalization across a single Josephson junction}},
doi = {10.1103/PRXQuantum.2.040341},
volume = {2},
year = {2021},
}
@misc{13056,
abstract = {This datasets comprises all data shown in plots of the submitted article "Converting microwave and telecom photons with a silicon photonic nanomechanical interface". Additional raw data are available from the corresponding author on reasonable request.},
author = {Arnold, Georg M and Wulf, Matthias and Barzanjeh, Shabir and Redchenko, Elena and Rueda Sanchez, Alfredo R and Hease, William J and Hassani, Farid and Fink, Johannes M},
publisher = {Zenodo},
title = {{Converting microwave and telecom photons with a silicon photonic nanomechanical interface}},
doi = {10.5281/ZENODO.3961561},
year = {2020},
}
@misc{13070,
abstract = {This dataset comprises all data shown in the figures of the submitted article "Surpassing the resistance quantum with a geometric superinductor". Additional raw data are available from the corresponding author on reasonable request.},
author = {Peruzzo, Matilda and Trioni, Andrea and Hassani, Farid and Zemlicka, Martin and Fink, Johannes M},
publisher = {Zenodo},
title = {{Surpassing the resistance quantum with a geometric superinductor}},
doi = {10.5281/ZENODO.4052882},
year = {2020},
}
@misc{13071,
abstract = {This dataset comprises all data shown in the plots of the main part of the submitted article "Bidirectional Electro-Optic Wavelength Conversion in the Quantum Ground State". Additional raw data are available from the corresponding author on reasonable request.},
author = {Hease, William J and Rueda Sanchez, Alfredo R and Sahu, Rishabh and Wulf, Matthias and Arnold, Georg M and Schwefel, Harald and Fink, Johannes M},
publisher = {Zenodo},
title = {{Bidirectional electro-optic wavelength conversion in the quantum ground state}},
doi = {10.5281/ZENODO.4266025},
year = {2020},
}
@article{8529,
abstract = {Practical quantum networks require low-loss and noise-resilient optical interconnects as well as non-Gaussian resources for entanglement distillation and distributed quantum computation. The latter could be provided by superconducting circuits but existing solutions to interface the microwave and optical domains lack either scalability or efficiency, and in most cases the conversion noise is not known. In this work we utilize the unique opportunities of silicon photonics, cavity optomechanics and superconducting circuits to demonstrate a fully integrated, coherent transducer interfacing the microwave X and the telecom S bands with a total (internal) bidirectional transduction efficiency of 1.2% (135%) at millikelvin temperatures. The coupling relies solely on the radiation pressure interaction mediated by the femtometer-scale motion of two silicon nanobeams reaching a Vπ as low as 16 μV for sub-nanowatt pump powers. Without the associated optomechanical gain, we achieve a total (internal) pure conversion efficiency of up to 0.019% (1.6%), relevant for future noise-free operation on this qubit-compatible platform.},
author = {Arnold, Georg M and Wulf, Matthias and Barzanjeh, Shabir and Redchenko, Elena and Rueda Sanchez, Alfredo R and Hease, William J and Hassani, Farid and Fink, Johannes M},
issn = {2041-1723},
journal = {Nature Communications},
keywords = {General Biochemistry, Genetics and Molecular Biology, General Physics and Astronomy, General Chemistry},
publisher = {Springer Nature},
title = {{Converting microwave and telecom photons with a silicon photonic nanomechanical interface}},
doi = {10.1038/s41467-020-18269-z},
volume = {11},
year = {2020},
}
@article{8755,
abstract = {The superconducting circuit community has recently discovered the promising potential of superinductors. These circuit elements have a characteristic impedance exceeding the resistance quantum RQ ≈ 6.45 kΩ which leads to a suppression of ground state charge fluctuations. Applications include the realization of hardware protected qubits for fault tolerant quantum computing, improved coupling to small dipole moment objects and defining a new quantum metrology standard for the ampere. In this work we refute the widespread notion that superinductors can only be implemented based on kinetic inductance, i.e. using disordered superconductors or Josephson junction arrays. We present modeling, fabrication and characterization of 104 planar aluminum coil resonators with a characteristic impedance up to 30.9 kΩ at 5.6 GHz and a capacitance down to ≤ 1 fF, with lowloss and a power handling reaching 108 intra-cavity photons. Geometric superinductors are free of uncontrolled tunneling events and offer high reproducibility, linearity and the ability to couple magnetically - properties that significantly broaden the scope of future quantum circuits. },
author = {Peruzzo, Matilda and Trioni, Andrea and Hassani, Farid and Zemlicka, Martin and Fink, Johannes M},
issn = {23317019},
journal = {Physical Review Applied},
number = {4},
publisher = {American Physical Society},
title = {{Surpassing the resistance quantum with a geometric superinductor}},
doi = {10.1103/PhysRevApplied.14.044055},
volume = {14},
year = {2020},
}
@article{8944,
abstract = {Superconductor insulator transition in transverse magnetic field is studied in the highly disordered MoC film with the product of the Fermi momentum and the mean free path kF*l close to unity. Surprisingly, the Zeeman paramagnetic effects dominate over orbital coupling on both sides of the transition. In superconducting state it is evidenced by a high upper critical magnetic field 𝐵𝑐2, by its square root dependence on temperature, as well as by the Zeeman splitting of the quasiparticle density of states (DOS) measured by scanning tunneling microscopy. At 𝐵𝑐2 a logarithmic anomaly in DOS is observed. This anomaly is further enhanced in increasing magnetic field, which is explained by the Zeeman splitting of the Altshuler-Aronov DOS driving
the system into a more insulating or resistive state. Spin dependent Altshuler-Aronov correction is also needed to explain the transport behavior above 𝐵𝑐2.},
author = {Zemlicka, Martin and Kopčík, M. and Szabó, P. and Samuely, T. and Kačmarčík, J. and Neilinger, P. and Grajcar, M. and Samuely, P.},
issn = {24699969},
journal = {Physical Review B},
number = {18},
publisher = {American Physical Society},
title = {{Zeeman-driven superconductor-insulator transition in strongly disordered MoC films: Scanning tunneling microscopy and transport studies in a transverse magnetic field}},
doi = {10.1103/PhysRevB.102.180508},
volume = {102},
year = {2020},
}
@inproceedings{9001,
abstract = {Quantum illumination is a sensing technique that employs entangled signal-idler beams to improve the detection efficiency of low-reflectivity objects in environments with large thermal noise. The advantage over classical strategies is evident at low signal brightness, a feature which could make the protocol an ideal prototype for non-invasive scanning or low-power short-range radar. Here we experimentally investigate the concept of quantum illumination at microwave frequencies, by generating entangled fields using a Josephson parametric converter which are then amplified to illuminate a room-temperature object at a distance of 1 meter. Starting from experimental data, we simulate the case of perfect idler photon number detection, which results in a quantum advantage compared to the relative classical benchmark. Our results highlight the opportunities and challenges on the way towards a first room-temperature application of microwave quantum circuits.},
author = {Barzanjeh, Shabir and Pirandola, Stefano and Vitali, David and Fink, Johannes M},
booktitle = {IEEE National Radar Conference - Proceedings},
isbn = {9781728189420},
issn = {1097-5659},
location = {Florence, Italy},
number = {9},
publisher = {IEEE},
title = {{Microwave quantum illumination with a digital phase-conjugated receiver}},
doi = {10.1109/RadarConf2043947.2020.9266397},
volume = {2020},
year = {2020},
}
@article{9114,
abstract = {Microwave photonics lends the advantages of fiber optics to electronic sensing and communication systems. In contrast to nonlinear optics, electro-optic devices so far require classical modulation fields whose variance is dominated by electronic or thermal noise rather than quantum fluctuations. Here we demonstrate bidirectional single-sideband conversion of X band microwave to C band telecom light with a microwave mode occupancy as low as 0.025 ± 0.005 and an added output noise of less than or equal to 0.074 photons. This is facilitated by radiative cooling and a triply resonant ultra-low-loss transducer operating at millikelvin temperatures. The high bandwidth of 10.7 MHz and total (internal) photon conversion
efficiency of 0.03% (0.67%) combined with the extremely slow heating rate of 1.1 added output noise photons per second for the highest available pump power of 1.48 mW puts near-unity efficiency pulsed quantum transduction within reach. Together with the non-Gaussian resources of superconducting qubits this might provide the practical foundation to extend the range and scope of current quantum networks in analogy to electrical repeaters in classical fiber optic communication.},
author = {Hease, William J and Rueda Sanchez, Alfredo R and Sahu, Rishabh and Wulf, Matthias and Arnold, Georg M and Schwefel, Harald G.L. and Fink, Johannes M},
issn = {2691-3399},
journal = {PRX Quantum},
number = {2},
publisher = {American Physical Society},
title = {{Bidirectional electro-optic wavelength conversion in the quantum ground state}},
doi = {10.1103/prxquantum.1.020315},
volume = {1},
year = {2020},
}
@article{9194,
abstract = {Quantum transduction, the process of converting quantum signals from one form of energy to another, is an important area of quantum science and technology. The present perspective article reviews quantum transduction between microwave and optical photons, an area that has recently seen a lot of activity and progress because of its relevance for connecting superconducting quantum processors over long distances, among other applications. Our review covers the leading approaches to achieving such transduction, with an emphasis on those based on atomic ensembles, opto-electro-mechanics, and electro-optics. We briefly discuss relevant metrics from the point of view of different applications, as well as challenges for the future.},
author = {Lauk, Nikolai and Sinclair, Neil and Barzanjeh, Shabir and Covey, Jacob P and Saffman, Mark and Spiropulu, Maria and Simon, Christoph},
issn = {2058-9565},
journal = {Quantum Science and Technology},
number = {2},
publisher = {IOP Publishing},
title = {{Perspectives on quantum transduction}},
doi = {10.1088/2058-9565/ab788a},
volume = {5},
year = {2020},
}
@article{9195,
abstract = {Quantum information technology based on solid state qubits has created much interest in converting quantum states from the microwave to the optical domain. Optical photons, unlike microwave photons, can be transmitted by fiber, making them suitable for long distance quantum communication. Moreover, the optical domain offers access to a large set of very well‐developed quantum optical tools, such as highly efficient single‐photon detectors and long‐lived quantum memories. For a high fidelity microwave to optical transducer, efficient conversion at single photon level and low added noise is needed. Currently, the most promising approaches to build such systems are based on second‐order nonlinear phenomena such as optomechanical and electro‐optic interactions. Alternative approaches, although not yet as efficient, include magneto‐optical coupling and schemes based on isolated quantum systems like atoms, ions, or quantum dots. Herein, the necessary theoretical foundations for the most important microwave‐to‐optical conversion experiments are provided, their implementations are described, and the current limitations and future prospects are discussed.},
author = {Lambert, Nicholas J. and Rueda Sanchez, Alfredo R and Sedlmeir, Florian and Schwefel, Harald G. L.},
issn = {2511-9044},
journal = {Advanced Quantum Technologies},
number = {1},
publisher = {Wiley},
title = {{Coherent conversion between microwave and optical photons - An overview of physical implementations}},
doi = {10.1002/qute.201900077},
volume = {3},
year = {2020},
}