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Superconductive quantum circuits (SQCs) comprise quantized energy levels that may be coupled via microwave electromagnetic fields. Described in this way, one may draw a close analogy to atoms with internal (electronic) levels coupled by laser light fields. In this Letter, we present a superconductive analog to electromagnetically induced transparency (S-EIT) that utilizes SQC designs of present day experimental consideration. We discuss how S-EIT can be used to establish macroscopic coherence in such systems and, thereby, utilized as a sensitive probe of decoherence.PACS numbers: 42.50.GySuperconductive quantum circuits (SQCs) comprising mesoscopic Josephson junctions can exhibit quantum coherence amongst their macroscopically large degrees of freedom [1]. They exhibit quantized flux and/or charge states depending on their fabrication parameters, and the resultant quantized energy levels are analogous to the quantized internal levels of an atom. Spectroscopy, Rabi oscillation, and Ramsey interferometry experiments have demonstrated that SQCs behave as "artificial atoms" under carefully controlled conditions [2,3,4,5,6,7,8,9]. This Letter extends the SQC-atom analogy to another quantum optical effect associated with atoms: electromagnetically induced transparency (EIT) [10,11]. We propose the demonstration of microwave transparency using a superconductive analog to EIT (denoted S-EIT) in a superconductive circuit exhibiting two meta-stable states (e.g., a qubit) and a third, shorter-lived state (e.g., the readout state). We show that driving coherent microwave transitions between the qubit states and the readout state is a demonstration of S-EIT. We further propose a means to use S-EIT to experimentally probe the qubit decoherence rate in a sensitive manner. The philosophy is similar to that in Ref. 12, where it was proposed to use EIT to measure phase diffusion in atomic Bose-Einstein condensates.The three-level Λ system illustrated in Fig. 1a is a standard energy level structure utilized in EIT [10,11]. It comprises two meta-stable states |1 and |2 , each of which may be coupled to a third excited state |3 . In atoms, the meta-stable states are typically hyperfine or Zeeman levels, while state |3 is an excited electronic state that may spontaneously decay at a relatively fast rate Γ 3 . In an atomic EIT scheme, a resonant "probe" laser couples the |1 ↔ |3 transition, and a "control" laser couples the |2 ↔ |3 transition. The transition coupling strengths are characterized by their Rabi frequencies Ω j3 ≡ −d j3 · E j3 for j = 1, 2 respectively, where d j3 are the dipole matrix elements and E j3 are the slowly varying envelopes of the electric fields. For particular Rabi frequencies Ω j3 , the probe and control fields are effectively decoupled from the atoms by a destructive quantum interference between the states of the two driven transitions. The result is probe and control field transparency [10,11]. In more recent experiments, ultraslow light propagation due to EIT-based refractive index modifications in atomi...

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Ability to understand and model the performance limits of nanowire transistors is the key to design of next generation devices. Here, we report studies on high-mobility junction-less gate-all-around nanowire field effect transistor with carrier mobility reaching 2000 cm 2 /V.s at room temperature. Temperature-dependent transport measurements reveal activated transport at low temperatures due to surface donors, while at room temperature the transport shows a diffusive behavior. From the conductivity data, the extracted value of sound velocity in InAs nanowires is found to be an order less than the bulk. This low sound velocity is attributed to the extended crystal defects that ubiquitously appear in these nanowires. Analyzing the temperature-dependent mobility data, we identify the key scattering mechanisms limiting the carrier transport in these nanowires. Finally, using these scattering models, we perform drift-diffusion based transport simulations of a nanowire field-effect transistor and compare the device performances with experimental measurements. Our device modeling provides insight into performance limits of InAs nanowire transistors and can be used as a predictive methodology for nanowire-based integrated circuits. KEYWORDS :InAs, nanowire, scattering, transport, field-effect transistors.Field effect transistor is the building block of integrated circuits and is key to new technologies. The aggressive scaling has pushed the silicon-based planar Metal-Oxide Semiconductor Field Effect Transistor (MOSFET) technology to the point where transistor performances cannot be enhanced by simply reducing dimensions. For further scaling of the transistor, several 1 alternative materials (other than silicon) and device geometries have been investigated including the Fin-Field ‡ Currently with GlobalFoundaries Page 2 of 22 Effect Transistor 2,3 , Tri-gate 4 , Omega gate 5 , and Gate All-Around or wrap gate (GAA) devices 6 . Though the fabrication of GAA device geometry is much more complex in a top-down approach, GAA (wrap gate) devices offer higher performance due to its superior electrostatic controls compared to other geometries. In this work, we fabricate and evaluate the performance of high mobility InAs nanowire junctionless transistors (JLT), synthesised through a combination of a simpler bottom-up approach and conventional lithographic techniques 7 .Although, InAs nanowire devices 8-11 have higher mobility than silicon based devices, the mobility in nanowires is significantly lower than that of bulk InAs 7-9,12 due to a variety of factors including increased electron/hole scattering rates and surface scattering mechanisms 8 . A detailed understanding of various carrier scattering mechanisms is essential to be able to improve experimental methods to build higher performance nanowire transistors in the future. In this work, we develop microscopic models to understand the experimental data and the limitations of the performance of the fabricated InAs GAA junctionless InAs nanowire transistors. To do so, we first ...