Quantum Memristors

Technology based on memristors, resistors with memory whose resistance depends on the history of the crossing charges, has lately enhanced the classical paradigm of computation with neuromorphic architectures. However, in contrast to the known quantized models of passive circuit elements, such as inductors, capacitors or resistors, the design and realization of a quantum memristor is still missing. Here, we introduce the concept of a quantum memristor as a quantum dissipative device, whose decoherence mechanism is controlled by a continuous-measurement feedback scheme, which accounts for the memory. Indeed, we provide numerical simulations showing that memory effects actually persist in the quantum regime. Our quantization method, specifically designed for superconducting circuits, may be extended to other quantum platforms, allowing for memristor-type constructions in different quantum technologies. The proposed quantum memristor is then a building block for neuromorphic quantum computation and quantum simulations of non-Markovian systems

Solitonic Josephson-based meminductive systems

Memristors, memcapacitors, and meminductors represent an innovative generation of circuit elements whose properties depend on the state and history of the system. The hysteretic behavior of one of their constituent variables, is their distinctive fingerprint. This feature endows them with the ability to store and process information on the same physical location, a property that is expected to benefit many applications ranging from unconventional computing to adaptive electronics to robotics. Therefore, it is important to find appropriate memory elements that combine a wide range of memory states, long memory retention times, and protection against unavoidable noise. Although several physical systems belong to the general class of memelements, few of them combine these important physical features in a single component. Here, we demonstrate theoretically a superconducting memory based on solitonic long Josephson junctions. Moreover, since solitons are at the core of its operation, this system provides an intrinsic topological protection against external perturbations. We show that the Josephson critical current behaves hysteretically as an external magnetic field is properly swept. Accordingly, long Josephson junctions can be used as multi-state memories, with a controllable number of available states, and in other emerging areas such as memcomputing, i.e., computing directly in/by the memory

Memristors and Superconducting Quantum Interference Filters in RF Systems

<p>Complex nonlinear dynamical systems have been appeared in many fields of science and engineering. We are curious about two specific instances of those systems. Those two instances connect memristors and Josephson junctions to the electromagnetic fields. The first instance investigated microstrip patch antenna embedding dual memristors. This hybrid system produces broadband radiation in a narrow band radiation structure. The second one studies the novel ultra-sensitive magnetic field receiver implemented by superconducting quantum interference filters (SQIFs).</p><p>For the first instance, we notice that memristor has been proposed as the fourth passive element. We start with investigating the circuit model of this memristive element. Then, we embedded this circuit model into an EM radiation structure. We first report an efficient broadband electromagnetic radiation from a narrowband microstrip patch antenna. The directly modulated microstrip patch antenna system with dual memristors is calculated by using an integrated full-wave finite-difference time-domain solver and an embedded SPICE3 solver. Nonlinear transient electromagnetic responses are analyzed. The radiation frequency spectrum demonstrates the broadband radiation performance from the narrowband antenna system. We predict that the conceptual challenge of high frequency memristors will stimulate pioneering work in the fields of microwave and memristors.</p><p>For the second one, we predict that superconducting quantum interference filters (SQIFs) might play a key role in future quantum wireless communication systems. We analyze the dynamic behavior of this large-scale 2D DC SQIF (two-dimensional superconducting direct current quantum interference filter) array in a dynamic electromagnetic environment. The investigation under this framework starts from the SPICE circuit description of a RCSJ (resistively and capacitively shunted junction) model of a Josephson junction and then extends to the 2D SQIF with few device parameters. We separate the interface and the implementation of 2D DC SQIF. This approach can significantly improve circuit-level design efficiency of 2D SQIF array and ultimately allows us to accelerate the hybrid design with an electromagnetic radiation structure. Our findings on the average voltage response of this device offer compelling evidence that the bias static magnetic field plays a key role in designing an effective far-field magnetic field sensor. Since this device can function as both a robust and sensitive low noise pre-amplifier as well as a receiving antenna which only senses the magnetic field component of far-field electromagnetic wave signals, we call it magnetic-antenna or B-antenna. We believe that our research not only directly benefits the sensor design for Information Operations/Signals Intelligence (IO/SIGINT) applications in Very High Frequency/Ultra High Frequency (VHF/UHF) bands, but also opens new dimension of novel ultra-sensitive receiving antenna technology.</p>Dissertatio