24 results on '"Archana Kamal"'
Search Results
2. Delivery of a Jagged1-PEG-MAL hydrogel with pediatric human bone cells regenerates critically sized craniofacial bone defects
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Archana Kamalakar, Brendan Tobin, Sundus Kaimari, M Hope Robinson, Afra I Toma, Timothy Cha, Samir Chihab, Irica Moriarity, Surabhi Gautam, Pallavi Bhattaram, Shelly Abramowicz, Hicham Drissi, Andres Garcia, Levi Wood, and Steven L Goudy
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JAGGED1 ,bone regeneration ,craniofacial bone loss ,non-canonical JAG1–NOTCH pathways ,tissue regenerative therapy ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Current treatments for congenital and acquired craniofacial (CF) bone abnormalities are limited and costly. Conventional methods involve surgical correction, short-term stabilization, and long-term bone grafting, which may include problematic allografts and limited autografts. While bone morphogenetic protein 2 (BMP2) has been used for bone regeneration, it can cause bone overgrowth and life-threatening inflammation. Bone marrow-derived mesenchymal stem cell therapies, though promising, are not Food and Drug Administration approved and are resource intensive. Thus, there is a need for effective, affordable, and less side-effect-prone bone regenerative therapies. Previous research demonstrated that JAGGED1 induces osteoblast commitment in murine cranial neural crest cells through a NOTCH-dependent non-canonical pathway involving JAK2–STAT5. We hypothesize that delivery of JAGGED1 and induction of its downstream NOTCH non-canonical signaling in pediatric human osteoblasts constitutes an effective bone regenerative treatment. Delivering pediatric human bone-derived osteoblast-like cells to an in vivo murine bone loss model of a critically sized cranial defect, we identified that JAGGED1 promotes human pediatric osteoblast commitment and bone formation through p70 S6K phosphorylation. This approach highlights the potential of JAGGED1 and its downstream activators as innovative treatments for pediatric CF bone loss.
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- 2024
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3. Strong coupling diagnostics for multi-mode open systems
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A. Metelmann, Archana Kamal, C. Kow, and Zhihao Xiao
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Physics ,Quantum Physics ,Multi-mode optical fiber ,500 Naturwissenschaften und Mathematik::530 Physik::530 Physik ,FOS: Physical sciences ,Quantum correlations in quantum information ,Open quantum systems & decoherence ,Quantum information with hybrid systems ,Strong coupling ,Statistical physics ,Quantum Physics (quant-ph) ,Eigenvalues and eigenvectors - Abstract
We present a new method to diagnose strong coupling in multi-mode open systems. Our method presents a non-trivial extension of exceptional point (EP) analysis employed for such systems; specifically, we show how eigenvectors can not only reproduce all the features predicted by EPs but are also able to identify the physical modes that hybridize in different regions of the strong coupling regime. As a demonstration, we apply this method to study hybridization physics in a three-mode optomechanical system and determine the parameter regime for efficient sideband cooling of the mechanical oscillator in the presence of reservoir correlations., 10+ pages, 6 figures
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- 2020
4. Suppressing relaxation in superconducting qubits by quasiparticle pumping
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Danna Rosenberg, Adam Sears, S. J. Weber, Jeffrey Birenbaum, Fei Yan, Archana Kamal, John Clarke, Jonilyn Yoder, Gianluigi Catelani, David Hover, Terry P. Orlando, Gabriel Samach, Jonas Bylander, Yasunobu Nakamura, Simon Gustavsson, William D. Oliver, Andrew J. Kerman, and Fumiki Yoshihara
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Superconductivity ,Physics ,Quantum Physics ,Multidisciplinary ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity ,Dephasing ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Superconductivity (cond-mat.supr-con) ,Quantum mechanics ,Qubit ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Quasiparticle ,Reversing ,Quantum Physics (quant-ph) ,010306 general physics ,0210 nano-technology ,Environmental noise ,Quantum ,Coherence (physics) - Abstract
Extending qubit lifetime through a shaped environment Qubits are the quantum two-level systems that encode and process information in quantum computing. Kept in isolation, qubits can be stable. In a practical setting, however, qubits must be addressed and interact with each other. Such an environment is typically viewed as a source of decoherence and has a detrimental effect on a qubit's ability to retain encoded information. Gustavsson et al. used a sequence of pulses as a source of “environment shaping” that could substantially increase the coherence time of a superconducting qubit. Science , this issue p. 1573
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- 2016
5. Quantum versus classical switching dynamics of driven-dissipative Kerr resonators
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Archana Kamal, Michel Devoret, Christian Kraglund Andersen, Alexandre Blais, Nicholas Masluk, and Ioan Pop
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Physics ,Josephson effect ,Quantum Physics ,Mesoscopic physics ,Bistability ,Dephasing ,General Physics and Astronomy ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Kinetic inductance ,3. Good health ,Nonlinear system ,Nonlinear resonance ,Quantum electrodynamics ,0103 physical sciences ,Dissipative system ,010306 general physics ,0210 nano-technology ,Quantum Physics (quant-ph) - Abstract
We report a first-principles study of the driven dissipative dynamics for Kerr oscillators in the mesoscopic regime. This regime is characterized by large Kerr nonlinearity, realized here using the nonlinear kinetic inductance of a large array of Josephson junctions. The experimentally measured nonlinear resonance lineshapes of the junction array modes show significant deviations from steady-state numerical predictions, and necessitate time-dependent numerical simulations indicative of strong measurement-induced dephasing in the system arising from the large cross-Kerr effect between array modes. Analytical and numerical calculations of switching rate corroborate this by showing the emergence of a slow time scale, which is much longer than the linear decay rate and is set by fluctuation-induced switching times in the bistable regime. Furthermore, our analysis shows that the usual quantum-activated escape treatment is inadequate for prediction of the switching rates at large frequency shifts caused by strong nonlinearities, necessitating a quantum treatment that utilizes the full system Liouvillian. Based on our analysis, we identify a universal crossover parameter that delineates the regimes of validity of semiclassical and quantum descriptions, respectively. Our work shows how dynamical switching effects in strongly nonlinear systems provide a platform to study quantum-to-classical transitions., Comment: 16 pages, 9 figures
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- 2019
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6. High-fidelity dissipative engineering using parametric interactions
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Archana Kamal, Leonardo Ranzani, E. Doucet, and Florentin Reiter
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Bell state ,Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Computer science ,FOS: Physical sciences ,Dissipation ,High fidelity ,Control theory ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Dissipative system ,Quantum Physics (quant-ph) ,Protocol (object-oriented programming) ,Parametric statistics - Abstract
Established methods for dissipative state preparation typically rely on resolving resonances, limiting the target state fidelity due to competition between the stabilization mechanism and uncontrolled dissipation. We propose a protocol devoid of such constraints, using parametric couplings to engineer dissipation for preparation of any maximally entangled two-qubit state. Our scheme allows high-fidelity entanglement generation with short convergence time, continuous control of the target state in the stabilized manifold, and is realizable with state-of-the-art superconducting qubit technology., Comment: 6 pages, 4 figures + supplement
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- 2018
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7. Biomedical engineering approaches for the delivery of JAGGED1 as a potential tissue regenerative therapy
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Sundus Kaimari, Archana Kamalakar, and Steven L. Goudy
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JAGGED1 ,NOTCH signaling pathway ,tissue regenerative therapy ,JAGGED1 delivery ,biomaterials ,Biotechnology ,TP248.13-248.65 - Abstract
JAG1 is a ligand that activates the NOTCH signaling pathway which plays a crucial role in determining cell fate behavior through cell-to-cell signaling. JAG1-NOTCH signaling is required for mesenchymal stem cell (MSC) differentiation into cardiomyocytes and cranial neural crest (CNC) cells differentiation into osteoblasts, making it a regenerative candidate for clinical therapy to treat craniofacial bone loss and myocardial infarction. However, delivery of soluble JAG1 has been found to inhibit NOTCH signaling due to the requirement of JAG1 presentation in a bound form. For JAG1-NOTCH signaling to occur, JAG1 must be immobilized within a scaffold and the correct orientation between the NOTCH receptor and JAG1 must be achieved. The lack of clinically translatable JAG1 delivery methods has driven the exploration of alternative immobilization approaches. This review discusses the role of JAG1 in disease, the clinical role of JAG1 as a treatment, and summarizes current approaches for JAG1 delivery. An in-depth review was conducted on literature that used both in vivo and in vitro delivery models and observed the canonical versus non-canonical NOTCH pathway activated by JAG1. Studies were then compared and evaluated based on delivery success, functional outcomes, and translatability. Delivering JAG1 to harness its ability to control cell fate has the potential to serve as a therapeutic for many diseases.
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- 2023
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8. Open quantum cosmological system
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Sarah Shandera, Archana Kamal, Nishant Agarwal, Massachusetts Institute of Technology. Research Laboratory of Electronics, and Kamal, Archana
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Physics ,Density matrix ,010308 nuclear & particles physics ,Scalar (mathematics) ,Scalar theories of gravitation ,01 natural sciences ,Momentum ,Classical mechanics ,De Sitter universe ,0103 physical sciences ,Anti-de Sitter space ,010306 general physics ,Scalar field ,de Sitter invariant special relativity - Abstract
We derive the evolution equation for the density matrix of a UV- and IR- limited band of comoving momentum modes of the canonically normalized scalar degree of freedom in two examples of nearly de Sitter universes. Including the effects of a cubic interaction term from the gravitational action and tracing out a set of longer wavelength modes, we find that the evolution of the system is non-Hamiltonian and non-Markovian. We find linear dissipation terms for a few modes with wavelength near the boundary between system and bath, and nonlinear dissipation terms for all modes. The non-Hamiltonian terms in the evolution equation persist to late times when the scalar field dynamics is such that the curvature perturbation continues to evolve on super-Hubble scales.
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- 2017
9. Minimal models for nonreciprocal amplification using biharmonic drives
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Archana Kamal and A. Metelmann
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Quantum Physics ,Boosting (machine learning) ,Condensed Matter - Mesoscale and Nanoscale Physics ,Computer science ,Amplifier ,Circulator ,General Physics and Astronomy ,FOS: Physical sciences ,Scalable architecture ,Minimal models ,Quantum information processing ,01 natural sciences ,010305 fluids & plasmas ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Biharmonic equation ,Electronic engineering ,010306 general physics ,Quantum Physics (quant-ph) ,Quantum - Abstract
We present a generic system of three harmonic modes coupled parametrically with a time-varying coupling modulated by a combination of two pump harmonics, and show how this system provides the minimal platform to realize nonreciprocal couplings that can lead to gainless photon circulation, and phase-preserving or phase-sensitive directional amplification. Explicit frequency-dependent calculations within this minimal paradigm highlight the separation of amplification and directionality bandwidths, universal in such schemes. We also study the influence of counter-rotating interactions that can adversely affect directionality and associated bandwidth; we find that these effects can be mitigated by suitably designing the properties of the auxiliary mode that plays the role of an engineered reservoir to the amplification mode space., Comment: 10+ pages, including 6 figures + 2 appendices
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- 2016
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10. The Flux Qubit Revisited to Enhance Coherence and Reproducibility
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Andrew J. Kerman, Fei Yan, Terry P. Orlando, Jeffrey Birenbaum, Theodore Gudmundsen, William D. Oliver, S. J. Weber, Adam Sears, John Clarke, David Hover, Gabriel Samach, Danna Rosenberg, Simon Gustavsson, Archana Kamal, Jonilyn Yoder, Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Research Laboratory of Electronics, Yan, Fei, Gustavsson, Simon, Kamal, Archana, Orlando, Terry Philip, and Oliver, William D
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Flux qubit ,Charge qubit ,Science ,Dephasing ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,Phase qubit ,Computer Science::Emerging Technologies ,Quantum mechanics ,0103 physical sciences ,010306 general physics ,Quantum information science ,Physics ,Quantum Physics ,Multidisciplinary ,Shot noise ,General Chemistry ,021001 nanoscience & nanotechnology ,Qubit ,Quantum Physics (quant-ph) ,0210 nano-technology ,Superconducting quantum computing - Abstract
The scalable application of quantum information science will stand on reproducible and controllable high-coherence quantum bits (qubits). Here, we revisit the design and fabrication of the superconducting flux qubit, achieving a planar device with broad-frequency tunability, strong anharmonicity, high reproducibility and relaxation times in excess of 40 μs at its flux-insensitive point. Qubit relaxation times T1 across 22 qubits are consistently matched with a single model involving resonator loss, ohmic charge noise and 1/f-flux noise, a noise source previously considered primarily in the context of dephasing. We furthermore demonstrate that qubit dephasing at the flux-insensitive point is dominated by residual thermal-photons in the readout resonator. The resulting photon shot noise is mitigated using a dynamical decoupling protocol, resulting in T2≈85 μs, approximately the 2T1 limit. In addition to realizing an improved flux qubit, our results uniquely identify photon shot noise as limiting T2 in contemporary qubits based on transverse qubit–resonator interaction., Scalable quantum information processing requires controllable high-coherence qubits. Here, the authors present superconducting flux qubits with broad frequency tunability, strong anharmonicity and high reproducibility, identifying photon shot noise as the main source of dephasing for further improvements.
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- 2015
11. Heisenberg-Limited Qubit Read-Out with Two-Mode Squeezed Light
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Nicolas Didier, William D. Oliver, Alexandre Blais, Archana Kamal, and Aashish A. Clerk
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Physics ,Coupling ,Quantum Physics ,Flux qubit ,Charge qubit ,Condensed Matter - Mesoscale and Nanoscale Physics ,FOS: Physical sciences ,General Physics and Astronomy ,Phase qubit ,Circuit quantum electrodynamics ,Quantum electrodynamics ,Quantum mechanics ,Qubit ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Quantum information ,Quantum Physics (quant-ph) ,Squeezed coherent state - Abstract
We show how to use two-mode squeezed light to exponentially enhance cavity-based dispersive qubit measurement. Our scheme enables true Heisenberg-limited scaling of the measurement, and crucially, is not restricted to small dispersive couplings or unrealistically long measurement times. It involves coupling a qubit dispersively to two cavities, and making use of a symmetry in the dynamics of joint cavity quadratures (a so-called quantum-mechanics-free subsystem). We discuss the basic scaling of the scheme and its robustness against imperfections, as well as a realistic implementation in circuit quantum electrodynamics., Comment: 5 pages, 4 figures, Supplemental Material
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- 2015
12. Thermal and Residual Excited-State Population in a 3D Transmon Qubit
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Archana Kamal, Jovi Miloshi, William D. Oliver, David Hover, Rick Slattery, Simon Gustavsson, Terry P. Orlando, Theodore Gudmundsen, Adam Sears, Jonilyn Yoder, Xiaoyue Jin, and Fei Yan
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Physics ,education.field_of_study ,Quantum Physics ,Condensed Matter - Superconductivity ,Population ,FOS: Physical sciences ,General Physics and Astronomy ,Transmon ,Residual ,Superconductivity (cond-mat.supr-con) ,Qubit ,Excited state ,Quantum mechanics ,Thermal ,Quantum Physics (quant-ph) ,education ,Quantum computer - Abstract
Remarkable advancements in coherence and control fidelity have been achieved in recent years with cryogenic solid-state qubits. Nonetheless, thermalizing such devices to their milliKelvin environments has remained a long-standing fundamental and technical challenge. In this context, we present a systematic study of the first-excited-state population in a 3D transmon superconducting qubit mounted in a dilution refrigerator with a variable temperature. Using a modified version of the protocol developed by Geerlings et al., we observe the excited-state population to be consistent with a Maxwell-Boltzmann distribution, i.e., a qubit in thermal equilibrium with the refrigerator, over the temperature range 35-150 mK. Below 35 mK, the excited-state population saturates at approximately 0.1%. We verified this result using a flux qubit with ten times stronger coupling to its readout resonator. We conclude that these qubits have effective temperature T(eff)=35 mK. Assuming T(eff) is due solely to hot quasiparticles, the inferred qubit lifetime is 108 μs and in plausible agreement with the measured 80 μs.
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- 2014
13. Query based performance analysis of row and column storage data warehouse
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Suresh C. Gupta and Archana Kamal
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Database ,Computer science ,Data manipulation language ,Online analytical processing ,Data transformation ,InformationSystems_DATABASEMANAGEMENT ,Dimensional modeling ,computer.software_genre ,Column (database) ,Data warehouse ,Data modeling ,Operating system ,Online transaction processing ,computer - Abstract
Row based relational database management systems (R-RDBMS) are the most common choice for data warehouse implementations. Row based storage is useful in online transaction processing (OLTP) to insert and update data while column oriented RDBMS (C-RDBMS) in online analytical processing (OLAP) to access data from data warehouse. This paper analyses the best suited mode of storage (row or column based storage) for different type of data manipulation language (DML) queries in data warehouse. It also evaluates and compares the performance of row and column oriented data structures based on elapsed time, CPU, I/O and operator costs; for different types of DML queries. A data warehouse has been designed for simulation purpose using Red Gate Data Generator tool along with Microsoft SQL Server 2012.
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- 2014
14. A novel cell selection method for LTE HetNet
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Archana Kamal and Vineetha Mathai
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Computer science ,business.industry ,Femto ,Macro cell ,Throughput ,Cell selection ,law.invention ,Power (physics) ,Relay ,law ,Limit (music) ,business ,Heterogeneous network ,Computer network - Abstract
In LTE-A system, heterogeneous network (HetNet) consisting of macro nodes and low power nodes such as pico nodes, femto nodes and relay nodes are deployed along with traditional macro only deployment to improve the system capacity. We have to balance the load between macro and low power nodes to improve the system performance. Cell selection plays an important role in balancing the system load and thus overall performance of the system. RSRP and CRE are the two conventional cell selection methods employed in LTE Hetnet. In RSRP method most of the UEs will select high power macro cell. This can limit the cell splitting gain. An alternative to this is to increase the range of pico cell by adding a bias to the Reference signal received power (RSRP) from the pico cell (Cell Range Expansion (CER) method). This cause UEs within the Range Expansion (RE) region to get attached to pico cell without considering the capacity of the pico cell, which will reduce the system performance. This paper propose a new cell selection method called Network coordinated cell selection (NC) which allow a UE within the RE region to be offloaded to pico cell based on the load of the pico cell and the achievable throughput. Simulation results shows that this method can achieve better performance than conventional cell selection methods.
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- 2014
15. Effects of aggregation and data size on query performance and memory requirements of a Data Warehouse
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Alok Dubey, Archana Kamal, and Suresh C. Gupta
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Database ,Computer science ,Aggregate (data warehouse) ,InformationSystems_DATABASEMANAGEMENT ,Dimensional modeling ,computer.software_genre ,Query optimization ,Language Integrated Query ,Data warehouse ,In-Memory Processing ,Sargable ,Query by Example ,computer ,computer.programming_language - Abstract
Aggregation is a key technique to enhance query response time in a large data warehouse. This paper analyzes its effects on query performance and memory requirements. A grocery shop data warehouse has been designed for simulation purpose using Red Gate Data Generator tool along with the Business Intelligence Development Studio of Microsoft SQL Server 2008. For a desired performance gain, the requirements on aggregate and its impact on memory usage has been studied. The effects of variation in size of base cube of a Data Warehouse on memory requirement and performance gain have also been analyzed.
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- 2014
16. Asymmetric frequency conversion in nonlinear systems driven by a biharmonic pump
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Michel Devoret, Ananda L. Roy, Archana Kamal, and John Clarke
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Physics ,Josephson effect ,Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Process (computing) ,General Physics and Astronomy ,FOS: Physical sciences ,Mechanics ,Nonlinear system ,Frequency conversion ,Harmonics ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Biharmonic equation ,Current (fluid) ,Quantum Physics (quant-ph) ,Realization (systems) ,Physics - Optics ,Optics (physics.optics) - Abstract
A novel mechanism of asymmetric frequency conversion is investigated in nonlinear dispersive devices driven parametrically with a biharmonic pump. When the relative phase between the first and second harmonics combined in a two-tone pump is appropriately tuned, nonreciprocal frequency conversion, either upward or downward, can occur. Full directionality and efficiency of the conversion process is possible, provided that the distribution of pump power over the harmonics is set correctly. While this asymmetric conversion effect is generic, we describe its practical realization in a model system consisting of a current-biased, resistively-shunted Josephson junction (RSJ). Here, the multiharmonic Josephson oscillations, generated internally from the static current bias, provide the pump drive., Comment: 5+ pages, 4 pages supplement. Expanded and modified discussion, additional references and a new appendix in supplemental material detailing the calculation of Josephson harmonics in the RSJ
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- 2014
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17. Coherence and Decay of Higher Energy Levels of a Superconducting Transmon Qubit
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Samuel James Bader, Theodore Gudmundsen, Peter Leek, Xiaoyue Jin, Archana Kamal, Michael Peterer, William D. Oliver, Terry P. Orlando, Simon Gustavsson, and Fei Yan
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Physics ,Quantum Physics ,Charge qubit ,Condensed Matter - Mesoscale and Nanoscale Physics ,General Physics and Astronomy ,FOS: Physical sciences ,Transmon ,01 natural sciences ,010305 fluids & plasmas ,Phase qubit ,Qubit ,Excited state ,Quantum mechanics ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Quantum information ,010306 general physics ,Ground state ,Quantum Physics (quant-ph) ,Coherence (physics) - Abstract
We present measurements of coherence and successive decay dynamics of higher energy levels of a superconducting transmon qubit. By applying consecutive $\pi$-pulses for each sequential transition frequency, we excite the qubit from the ground state up to its fourth excited level and characterize the decay and coherence of each state. We find the decay to proceed mainly sequentially, with relaxation times in excess of 20 $\mu$s for all transitions. We also provide a direct measurement of the charge dispersion of these levels by analyzing beating patterns in Ramsey fringes. The results demonstrate the feasibility of using higher levels in transmon qubits for encoding quantum information., Comment: Minor corrections. Added two plots in Figure 2. Added figures of the setup and the Ramsey fits in the supplemental material, as as more details on the device characterization. Rephrased last paragraph on charge dissipation. Added some references
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- 2014
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18. Microwave characterization of Josephson junction arrays: implementing a low loss superinductance
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Archana Kamal, Zlatko Minev, Nicholas Masluk, Michel Devoret, and Ioan Pop
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Physics ,Quantum phase transition ,Superconductivity ,Josephson effect ,business.industry ,Coplanar waveguide ,General Physics and Astronomy ,Electrical element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Resonator ,0103 physical sciences ,Optoelectronics ,Quantum information ,010306 general physics ,0210 nano-technology ,business ,Microwave - Abstract
We have measured the plasma resonances of an array of Josephson junctions in the regime E(J)>>E(C), up to the ninth harmonic by incorporating it as part of a resonator capacitively coupled to a coplanar waveguide. From the characteristics of the resonances, we infer the successful implementation of a superinductance, an electrical element with a nondissipative impedance greater than the resistance quantum [R(Q)=h/(2e)(2) is approximately equal to 6.5 kΩ] at microwave frequencies. Such an element is crucial for preserving the quantum coherence in circuits exploiting large fluctuations of the superconducting phase. Our results show internal losses less than 20 ppm, self-resonant frequencies greater than 10 GHz, and phase-slip rates less than 1 mHz, enabling direct application of such arrays for quantum information and metrology. Arrays with a loop geometry also demonstrate a new manifestation of flux quantization in a dispersive analog of the Little-Parks effect.
- Published
- 2012
19. Gain, directionality and noise in microwave SQUID amplifiers: Input-output approach
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Archana Kamal, John Clarke, and Michel Devoret
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Physics ,Josephson effect ,Quantum Physics ,Microwave amplifiers ,Scattering ,Amplifier ,Condensed Matter - Superconductivity ,FOS: Physical sciences ,Biasing ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Superconductivity (cond-mat.supr-con) ,Harmonics ,Condensed Matter::Superconductivity ,Electronic engineering ,Directionality ,Quantum Physics (quant-ph) ,Microwave - Abstract
We present a new theoretical framework to analyze microwave amplifiers based on the dc SQUID. Our analysis applies input-output theory generalized for Josephson junction devices biased in the running state. Using this approach we express the high frequency dynamics of the SQUID as a scattering between the participating modes. This enables us to elucidate the inherently nonreciprocal nature of gain as a function of bias current and input frequency. This method can, in principle, accommodate an arbitrary number of Josephson harmonics generated in the running state of the junction. We report detailed calculations taking into account the first few harmonics that provide simple semi-quantitative results showing a degradation of gain, directionality and noise of the device as a function of increasing signal frequency. We also discuss the fundamental limits on device performance and applications of this formalism to real devices., 12+ pages, 12 figures, 2 appendices
- Published
- 2012
20. Evidence for coherent quantum phase slips across a Josephson junction array
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Leonid I. Glazman, Jens Koch, Nicholas Masluk, Archana Kamal, Vladimir E. Manucharyan, and Michel Devoret
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Quantum phase transition ,Physics ,Josephson effect ,Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Condensed Matter - Superconductivity ,Quantum wire ,Dephasing ,FOS: Physical sciences ,Order (ring theory) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Electronic, Optical and Magnetic Materials ,Superconductivity (cond-mat.supr-con) ,Pi Josephson junction ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Quantum Physics (quant-ph) ,010306 general physics ,Energy (signal processing) ,Long Josephson junction - Abstract
Superconducting order in a sufficiently narrow and infinitely long wire is destroyed at zero temperature by quantum fluctuations, which induce $2\pi$ slips of the phase of the order parameter. However, in a finite-length wire coherent quantum phase-slips would manifest themselves simply as shifts of energy levels in the excitations spectrum of an electrical circuit incorporating this wire. The higher the phase-slips probability amplitude, the larger are the shifts. Phase-slips occurring at different locations along the wire interfere with each other. Due to the Aharonov-Casher effect, the resulting full amplitude of a phase-slip depends on the offset charges surrounding the wire. Slow temporal fluctuations of the offset charges make the phase-slips amplitudes random functions of time, and therefore turn energy levels shifts into linewidths. We experimentally observed this effect on a long Josephson junction array acting as a "slippery" wire. The slip-induced linewidths, despite being only of order 100 kHz, were resolved from the flux-dependent dephasing of the fluxonium qubit., Comment: 15 pages
- Published
- 2012
21. Alignments in quasar polarizations: Pseudoscalar-photon mixing in the presence of correlated magnetic fields
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Archana Kamal, Pankaj Jain, and Nishant Agarwal
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Physics ,Nuclear and High Energy Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Photon ,Magnetic domain ,FOS: Physical sciences ,Quasar ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Polarization (waves) ,Electromagnetic radiation ,Redshift ,Magnetic field ,High Energy Physics - Phenomenology ,symbols.namesake ,High Energy Physics - Phenomenology (hep-ph) ,symbols ,Stokes parameters ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We investigate the effects of pseudoscalar-photon mixing on electromagnetic radiation in the presence of correlated extragalactic magnetic fields. We model the Universe as a collection of magnetic domains and study the propagation of radiation through them. This leads to correlations between Stokes parameters over large scales and consistently explains the observed large-scale alignment of quasar polarizations at different redshifts within the framework of the big bang model., Comment: 12 pages, 5 figures, version published in PRD
- Published
- 2011
22. Noiseless nonreciprocity in a parametric active device
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Michel Devoret, Archana Kamal, and John Clarke
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Physics ,Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,business.industry ,Amplifier ,FOS: Physical sciences ,General Physics and Astronomy ,Chip ,Computer Science::Emerging Technologies ,Optics ,Cascade ,Reciprocity (electromagnetism) ,Qubit ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Quantum Physics (quant-ph) ,business ,Parametric statistics ,Electronic circuit ,Quantum computer - Abstract
Nonreciprocal devices such as circulators and isolators belong to an important class of microwave components employed in applications like the measurement of mesoscopic circuits at cryogenic temperatures. The measurement protocols usually involve an amplification chain which relies on circulators to separate input and output channels and to suppress backaction from different stages on the sample under test. In these devices the usual reciprocal symmetry of circuits is broken by the phenomenon of Faraday rotation based on magnetic materials and fields. However, magnets are averse to on-chip integration, and magnetic fields are deleterious to delicate superconducting devices. Here we present a new proposal combining two stages of parametric modulation emulating the action of a circulator. It is devoid of magnetic components and suitable for on-chip integration. As the design is free of any dissipative elements and based on reversible operation, the device operates noiselessly, giving it an important advantage over other nonreciprocal active devices for quantum information processing applications., 17 pages, 4 figures + 12 pages Supplementary Information
- Published
- 2010
23. 3D Bioprinted Bacteriostatic Hyperelastic Bone Scaffold for Damage-Specific Bone Regeneration
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Mohammadreza Shokouhimehr, Andrea S. Theus, Archana Kamalakar, Liqun Ning, Cong Cao, Martin L. Tomov, Jarred M. Kaiser, Steven Goudy, Nick J. Willett, Ho Won Jang, Christopher N. LaRock, Philip Hanna, Aron Lechtig, Mohamed Yousef, Janaina Da Silva Martins, Ara Nazarian, Mitchel B. Harris, Morteza Mahmoudi, and Vahid Serpooshan
- Subjects
damage-specific scaffold ,bone 3D bioprinting ,tissue engineering ,hyperelastic bone ,superparamagnetic iron oxide nanoparticles ,antibacterial ,Organic chemistry ,QD241-441 - Abstract
Current strategies for regeneration of large bone fractures yield limited clinical success mainly due to poor integration and healing. Multidisciplinary approaches in design and development of functional tissue engineered scaffolds are required to overcome these translational challenges. Here, a new generation of hyperelastic bone (HB) implants, loaded with superparamagnetic iron oxide nanoparticles (SPIONs), are 3D bioprinted and their regenerative effect on large non-healing bone fractures is studied. Scaffolds are bioprinted with the geometry that closely correspond to that of the bone defect, using an osteoconductive, highly elastic, surgically friendly bioink mainly composed of hydroxyapatite. Incorporation of SPIONs into HB bioink results in enhanced bacteriostatic properties of bone grafts while exhibiting no cytotoxicity. In vitro culture of mouse embryonic cells and human osteoblast-like cells remain viable and functional up to 14 days on printed HB scaffolds. Implantation of damage-specific bioprinted constructs into a rat model of femoral bone defect demonstrates significant regenerative effect over the 2-week time course. While no infection, immune rejection, or fibrotic encapsulation is observed, HB grafts show rapid integration with host tissue, ossification, and growth of new bone. These results suggest a great translational potential for 3D bioprinted HB scaffolds, laden with functional nanoparticles, for hard tissue engineering applications.
- Published
- 2021
- Full Text
- View/download PDF
24. Combined Effects of Viscosity Variation and Surface Roughness on the Squeeze Film Lubrication of Journal Bearings with Micropolar Fluids
- Author
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Neminath Bhujappa Naduvinamani, Siddangouda Apparao, Archana Kamalakar Kadadi, and Shivaraj Nagshetty Biradar
- Subjects
journal bearing ,surface roughness ,squeeze film ,micropolar fluid ,viscosity variation ,Physics ,QC1-999 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Mechanical engineering and machinery ,TJ1-1570 ,Chemistry ,QD1-999 - Abstract
In this paper, a theoretical study of the combined effects of viscosity variation and surface roughness on the squeeze film performance of journal bearings lubricated with micropolar fluid is made. The modified averaged Reynolds equation for micropolar fluids accounting for the randomized surface roughness structure and variation of viscosity is mathematically derived. The Christensen’s stochastic theory for hydrodynamic lubrication of rough surfaces is used to study the effect of two types of one dimensional surface roughness patterns on the squeeze film characteristics of a journal bearing with micropolar fluid. Closed form expressions for the mean pressure load carrying capacity are obtained for the infinitely short journal bearing. It is observed that, the transverse surface roughness pattern improves the squeeze film characteristics where as the adverse effects are observed for the one-dimensional longitudinal surface roughness pattern. The effect of variation of viscosity in micropolar fluid on the squeeze film characteristic of rough short journal bearings is analyzed.
- Published
- 2014
- Full Text
- View/download PDF
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