The Quantum Transport Laboratory
at IISER Thiruvananthapuram
Unveiling the Quantum Realm: Navigating the Qubit Frontier, Elevating Quantum Transport Research, and Shaping Tomorrow's Quantum Technologies.
Revolutionizing Device Technology
Electrical transport at quantizing dimensions is enriched by a number of exotic phenomena: quantum Hall effect, fractional quantum Hall effect, conductance quantization, flux-quantization, Aharanov-Bohm effect, single-electron tunneling, topologically protected states, etc., are a few to mention.
One important figure-of-merit of any scientific phenomena is its applicability in device technology. The outlook of our lab is to study, tailor, and utilize various quantum transport phenomena for improving our understanding of fundamental problems, pushing the limits, and revolutionizing device technology.
Latest Updates
Physical vapor deposition-free scalable high-efficiency electrical contacts to MoS2
Fermi-level pinning caused by the kinetic damage during metallization has been recognized as one of the majorreasons for the non-ideal behavior of electrical contacts, forbidding reaching the Schottky-Mott limit. In thismanuscript, we present a scalable technique wherein Indium, a low-work-function metal, is diffused to contact afew-layered MoS2 flake. The technique exploits a smooth outflow of Indium over gold electrodes to make edgecontacts to pre-transferred MoS2 flakes. We compare the performance of three pairs of contacts made onto thesame MoS2 flake, the bottom-gold, top-gold, and Indium contacts, and find that the Indium contacts are superiorto other contacts. The Indium contacts maintain linear I-V characteristics down to cryogenic temperatures with anextracted Schottky barrier height of ~ 2.1 meV. First-principle calculations show the induced in-gap states closeto the Fermi level, and the damage-free contact interface could be the reason for the nearly Ohmic behavior of theIndium/MoS2 interface.
For more details : https://doi.org/10.1088/1361-6528/ad12e4
Polymorphism-driven Distinct Nanomechanical, Optical, Photophysical, and Conducting Properties in a Benzothiophene-quinoline
Polymorphic forms of organic conjugated small molecules, with their unique molecular shapes, packing arrangements, and interaction patterns, provide an excellent opportunity to uncover how their microstructures influence their observable properties. Ethyl-2‐(1‐benzothiophene‐2‐yl)quinoline‐4‐carboxylate (BZQ) exists as dimorphs with distinct crystal habits―blocks(BZB) and needles (BZN). The crystal forms differ in their molecular arrangements―BZBhas a slip-stacked column-like structure in contrast to a zig-zag crystal packing with limited π–overlap in BZN. The BZBcrystals characterized by extended π-stacking along [100] demonstrated semiconductor behavior, whereas the BZN, with its zig-zag crystal packing and limited stacking characteristics, was reckoned as an insulator. Monotropically related crystal forms also differ in their nanomechanical properties, with BZBcrystals being considerably softer than BZNcrystals.
For more details : https://doi.org/10.1002/chem.202303558
Transient vortex dynamics and evolution of Bose metal from a 2D superconductor on MoS2
A metallic ground state in 2D is beyond the consensus of both Bosonic and Fermionic systems, and itsorigin and nature warrant a comprehensive theoretical understanding supplemented by in-depth experiments. A real-time observation of the influence of vortex dynamics on transport properties sofar has been elusive. We explore the nature and fate of a low-viscous, clean, 2D superconducting stateformed on an ionic-liquid gated few-layered MoS2 sample. The vortex-core being dissipative, the elasticdepinning, intervortex interaction, and the subsequent dynamics of the vortex-lattice leave transientsignatures in the transport characteristics. The temperature and magnetic field dependence of thetransient nature and the noise characteristics of the magnetoresistance confirm that quantum fluctuationsare solely responsible for the Bose metal state and the fragility of the superconducting state. .
For more details : https://doi.org/10.1088/2053-1583/ad0b87
GHz operation of a quantum point contact using stub-impedance matching circuit
In this work, we couple a QPC galvanically to a superconducting stub tuner impedance matching circuit realised in a coplanar waveguide architecture to enhance the operation frequency into the GHz regime and investigate the electrical amplification and complex admittance characteristics. The device, operating at ~ 1.96 GHz, exhibits a conductance sensitivity of 2.92×105(e2/h)/H1/2 with a bandwidth of 13 MHz.
For more details : https://doi.org/10.1016/j.physo.2023.100181
First Semiconducting Quantum Dot measured at QTran Lab
After many sleepless months, patience and teamwork, We at QTran Lab have finally developed India's First Semiconducting Quantum Dot. Quantum Dots are fundamental blocks of Spin Qubits and that would be our next step.
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Reach out to us
Feel free to get in touch with us! We're always excited to connect with fellow researchers, enthusiasts, and potential collaborators. Whether you're interested in our ongoing projects, seeking insights, or looking to explore new opportunities, we're here to engage in meaningful conversations that propel us into the future of quantum exploration.
Lab
Room No. 1203,
Physical Sciences Block,
IISER Thiruvananthapuram
Phone: 0471 2778085
Email: qtran@iisertvm.ac.in
Office
Room No. 2202,
Physical Sciences Block,
IISER Thiruvananthapuram
Phone: 0471 2778084
Email: madhu@iisertvm.ac.in
Funding and Support
We gratefully acknowledge the financial backing and collaboration from our sponsors. Their contributions play a pivotal role in advancing our research, enabling us to investigate the intricate world of quantum transport and its potential applications.
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Unlocking Quantum Mysteries: Our Research Journey
RESEARCH
Quantum transport research is at the forefront of understanding the behavior of particles and information at the quantum level, where traditional classical physics no longer holds true. This field investigates how electrons and other quantum particles move, interact, and transmit information in nanoscale systems. By unraveling the fundamental principles governing quantum transport, scientists gain insights into the behavior of matter at its smallest scales.
The outlook of our lab is to study, tailor, and utilize various quantum transport phenomena for improving our understanding of fundamental problems, pushing the limits, and revolutionizing device technology.
ONGOING PROJECTS
Semiconducting Spin Qubits
Semiconducting spin qubits currently represent a focal point in research endeavours due to their substantially prolonged coherence time and feasibility of integration into the established semiconductor industry. These spin qubits are typically fabricated using gate-defined coupled quantum dots formed on a two-dimensional electron gas interface within semiconducting heterostructures. When the individual spin states of two qubits are coupled, they give rise to two hybrid singlet and triplet states. These states exhibit a significant energy gap, making them controllable and in essence, serving as functional qubits in the realm of quantum information processing. This innovative approach holds significant promise for the advancement of quantum computing technologies.
Quantum Electrical Amplifiers
Highly sensitive devices are required to sense and detect current and electric field changes in a few electron regime. Non-linear devices such as quantum point contacts (QPC) or single electron transistors (SET) are capable of detecting even a single electron charge. These devices coupled with superconducting CPW resonators and impedance matching circuits can be used for readout of semiconducting qubits.
Superconducting resonators for spin-photon coupling
Superconducting coplanar waveguide (CPW) resonators are a crucial component in the field of quantum computing, specifically for controlling and reading out spin qubits. These resonators are fabricated using superconducting materials such as aluminium and niobium to create low-loss microwave circuits, enabling precise manipulation of the qubit states. By coupling spin qubits to CPW resonators, we can achieve efficient qubit control and high-fidelity qubit readout, advancing the development of quantum information processing technologies.
Superconducting Aluminium CPW resonators fabricated on sapphire
Superconducting stub tuner impedance matching circuit
The impedance mismatch between the measurement circuitry and high-impedance nanoscale devices such as QPCs, Quantum dots, etc limits the operational speed of these devices to the kHz regime in the conventional operational scheme. The stub-matching technique derived from microwave impedance matching enables operation at much higher operating frequencies, yields a larger bandwidth, and has a tunable load resistance.
Superconducting stub tuner fabricated on Sapphire, galvanically coupled to QPC
Broad-band electrical amplifier
Probing single charge dynamics in solids can give insights into various quantum transport phenomena, most of which are fragile and short-time-scaled. Detection of these events in real-time requires a mesoscopic electrical amplifier with unprecedented sensitivity and operational bandwidth. In this work, we explore a hybrid electrical amplifier consisting of a semiconducting quantum point contact galvanically coupled to a superconducting λ/2 transmission-line resonator for ultra-fast and ultra-sensitive charge amplification.
Superconducting resonator fgalvanically coupled to QPC
Quantum point contact charge sensors
One dimensional channel formed by electrostatic confinement with a point contact structure on a high mobility 2DEG. It shows variation in the conduction of the channel in steps of 2e2/h (G0) as the gate voltage is varied. In the pinch-off regime, high non-linearity of the device is highly sensitive to electrostatic field variation in the surroundings and allows to detect even in single electron regime.
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QPC device, potential profile and the conductance plateaus
Devices on vW Heterostructures
van der Waals (vW) materials offer a clean and uniform platform — unlike conventional 2DEG materials — and allows freedom to stack different candidates with varied properties; semiconducting, metallic or insulating. Their inherent 2D nature and substrate independence makes them an interesting candidate for quantum electronic devices. In addition, their high mechanical strength allows coupling of mechanical and electrical properties.
Electrostatic control of quantum phases using ionic liquid
Ionic liquid gating enables one to change the carrier concentration in a system by many orders, which is not possible in conventional dielectric gating techniques. Quantum phases such as 2D superconductivity can be realized and explored in vW systems using this technique. On systems that lack a center of symmetry, interesting features such as Ising superconductivity can be observed.
Read more...
Ionic liquid gating on MoS2
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Collaborations
Join us in advancing the frontiers of quantum transport research. Whether you're an academic researcher, student, industry expert, or enthusiast, we welcome collaborations that push the boundaries of knowledge. Explore research partnerships, student programs, visiting researcher opportunities, and industry collaborations. Let's shape the future of quantum together. Contact us at [qtran@iisertvm.ac.in] to get started.
Team
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Principal Investigator
Dr. Madhu Thalakulam
https://scholar.google.com/citations?user=3--YLbIAAAAJ&hl=en&oi=aoResearch Interests:
- Quantum transport: Transport in nanoscale devices such as QPCs, quantum dots, superconducting tunnel junction systems.
- High-frequency measurements: Radio-frequency reflectometry of nanoscale devices such as QPCs, Quantum dots etc.
- Solid state qubits: Single spin manipulation and detection in quantum dot qubits. Quantum measurement and back action in nanoscale devices.
- Devices on van der Waals materials and heterostructures
- Topological Insulators (TI) and TI based devices for spintronics
Contact:
+91 (0)471 - 2778084
Email:
madhu@iisertvm.ac.in
Education:
Ph.D. Applied Physics (Rice Quantum Institute, Rice University, Houston TX, May 2007. )
Post doctoral researcher (Quantum Phenomena Department, Sandia National Laboratory, Albuquerque, NM, USA.(2010-2012)). Post Doctoral Researcher (Silicon quantum computing group, University of Wisconsin, Madison, WI, USA.(2007-2010))
Doctoral Student
Sreevidya N
Research Interests:
- Phase Engineering of 2D MoS2 We explore the nature and fate of a clean, 2D superconducting state formed on an ionic-liquid gated few-layered MoS2 sample.
- Phase engineering of MoS2 is also important to design low-resistance contacts to realize FETs with enhanced performance.
Contact:
Email:
sreevidya18@iisertvm.ac.in
Education:
B.Sc Physics- Vimala College Thrissur, Calicut university; M.Sc Physics- NIT Calicut
Education:
B.Sc Physics - Government Victoria College, Palakkad; M.Sc Physics - Cochin University of Science and Technology.
Integrated PhD Student
Hari Krishnan S
Research Interests:
- Working towards the realisation of semiconducting spin qubits for quantum computing, which involves hybrid circuit QED where quantum dots are coupled to microwave resonators for qubit control, readout and long range spin-spin coupling.
Contact:
Email:
sharik18@iisertvm.ac.in
Education:
B.Sc (Physics), Loyola College (Affiliated to University of Madras)
Education:
Masters in Physics from NIT Trichy in 2020.
Bachelor degree in Physical Sciences(Physics, Chemistry, and Mathematics) from Nrupathunga University, Bengaluru
Education:
Integrated BS-MS dual degree, with major in Physics and minor in Mathematics, from IISER-THIRIVANANTHAPURAM
Education:
MSc from National Institute of Technology, Tiruchirappalli
Doctoral Student
Dr. Prasantha Kumbhakar
Post Doctoral at the University of Basel, Switzerland.
Doctoral Student
Dr. Ashby Philip Johnson
Post Doctoral Researcher, University of Arkansas, USA
Doctoral Student
Dr. Chitra H. Sharma
Av Humboldt Fellow CHyN, Universitat Hamburg Hamburg, Germany
Gallery
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Empowering Innovation Through Advanced Facilities
Our state-of-the-art facilities provide the ideal environment for unraveling the mysteries of quantum phenomena and forging the future of transformative technologies.
Material Processing and Device Fabrication
Our laboratory specializes in advanced material processing techniques, allowing us to engineer materials with tailored properties, including lithographic techniques, thin film deposition, etching, and doping, to create the foundation for innovative quantum devices.
Electrical Characterization
Electrical characterization is a fundamental process in materials science and electronics, involving the measurement of electrical properties such as conductivity, resistivity, and carrier mobility. This technique provides crucial insights into the behavior and performance of electronic materials and devices, enabling advancements in fields like semiconductor technology and quantum electronics.
Experimental Facilities
Bluefors LD250 Dilution Refrigerator
The LD is the dilution refrigerator measurement system. It has best-in-class heat exchangers with superior performance. The LD250 system typically provides more than 15 μW at 20 mK on the experimental flange with only 18 liters of helium-3. In addition, it has a high cooling power of ∼ 0.5 mW when operated at 100 mK. It is capable of cooling down to 10mk and can be integrated with a superconducting solenoid magnet up to 8T.
4K Cryostat
Our laboratory houses a state-of-the-art 4K cryostat, an indispensable tool for conducting quantum transport experiments. It provides an ultra-low-temperature environment down to 4 Kelvin, creating ideal conditions for studying the quantum behavior of electronic systems.
Raith PIONEER 2 for electron beam lithography
The PIONEER Two integrates all the highest-performance ingredients for professional EBL and SEM imaging into a single complete turnkey system. Versatility, robustness, and user-friendliness make PIONEER Two suitable for all those not only seeking to “print” and re-inspect their nanostructures, but also wanting to access an analytical tool with capabilities for SEM imaging and chemical or structural analysis in materials or life sciences.
MicroWriter ML3 for direct-write(Maskless) lithography
MicroWriter ML3 is a compact, high-performance, direct-write optical lithography machine. Four different minimum feature sizes (0.6µm, 1µm, 2µm, and 5µm) can be selected automatically via software. This allows non-critical parts of the exposure to be performed rapidly while retaining high-resolution writing for critical parts. An additional 0.4µm minimum feature size is available as an option.
Wire bonder
Wire bonder is an essential tool for creating reliable electrical connections within our quantum devices. It enables precise wire bonding to semiconductor components, ensuring low-resistance, high-fidelity connections critical for quantum transport experiments.
Reactive Ion Etching (RIE)
Our facility is equipped with advanced Reactive Ion Etching tools, enabling precise and controlled removal of materials at the nanoscale. RIE is a crucial technique for sculpting intricate quantum device structures with exceptional accuracy.
MILA-5000 Annealer
The MILA-5000 series can perform high speed heating, high speed cooling, and clean heating, which are characteristics of the Infrared Gold Image Furnace. It can heat materials under adjustable atmospheres and combines a temperature controller and variable atmosphere chamber into a single low-cost infrared lamp heating system.
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Two Thermal Evaporators
Thermal evaporation is a common method of physical vapor deposition (PVD). It is one of the simplest forms of PVD and typically uses a resistive heat source to evaporate a solid material in a vacuum environment to form a thin film. The material is heated in a high vacuum chamber until vapor pressure is produced. The evaporated material, or vapor stream, traverses the vacuum chamber with thermal energy and coats the substrate.
vW heterostructure micropositioning (Lab-made)
Deterministic transfer of two dimensional crystals constitutes a crucial step towards the fabrication of hetero-structures based on artificial stacking of two dimensional van der waals materials. This setup allows for the placement of 2-D materials onto a user defined specific location with high accuracy and reliability.
UV- Mask Aligner (Lab-made)
A Mask aligner is a machine to transcribe a fine pattern on a substrate using UV light. Substrates are made of various materials, silicon, glass, ceramic, GaAs, quartz, etc. It is used in the manufacturing of semiconductor devices, such as general transistors and Integrated circuits, and also used for LCD glass patterns and quartz crystal units as well.
RF Measurements
Measurement electronics for RF measurements in dilution refrigerator- Vector Network analyzer, Signal generator, Spectrum analyzer, Oscilloscope...
Microwave Plasma Cleaner
Our laboratory is equipped with a cutting-edge microwave plasma cleaner, a vital tool for achieving pristine and contamination-free surfaces on our quantum devices. This technology efficiently removes organic residues and contaminants from samples, ensuring the highest quality interfaces for precise quantum transport measurements.
Tube Furnace
Our tube furnace is an integral part of our research infrastructure, empowering investigations into the fabrication and modification of quantum materials, essential for pioneering research in quantum transport and quantum electronics.
Explore the Latest Discoveries and Engage with Cutting-Edge Events
HIGHLIGHTS
Positions Available
Please contact Dr. Madhu Thalakulam -madhu@iisertvm.ac.in
Projects Available
Please contact Dr. Madhu Thalakulam -madhu@iisertvm.ac.in
LATEST NEWS
Semiconduction Quantum dot of Qtran
21/08/2023
We at QTran Lab -IISER TVM have finally developed India's first semiconducting quantum dot.
Read more ...
Congratulations to Master's Graduates!
21/08/2023
"Join us in congratulating the outstanding individuals who have successfully completed their Master's journey in our laboratory!"
Read more ...
Empowering Minds in the Quantum Universe:
Explore Our Cutting-Edge Courses and Resources for a Quantum Leap in Knowledge
Lectures, Talks and Resources
Thesis
- Growth and Characterisation of vW heterostructures (Arathi Das M. K.)
- Strain Engineering Bandgap and Piezoresistivity in Few-layer MoS2. (Arya T. )
- Automated electrical transport measurements for multi-gated quantum devices. Sangeeth S. Varma)
- Metallic like states on MoS2 using microwave plasma (Ananthu P. S)
- Patterned growth of Bismuth Selenide heterostructures for device applications (Alwyn Antony)
- Microwave Plasma assisted layer reduction and patterning of TMDCs for 2D device application (Abin Varghese)
- Effect of molecular packing on charge transfer and photoconductivity in single-crystal organic FETs. (Avirup Roy)
- Electronic transport in 2D layered field effect devices (Prafful Golani)
- unneling of fractional quantum hall quasi-particles in Quantum point contacts (Amandeep Singh)
- Fabrication and characterization of exfoliated Bi2Se3 and MoS2 devices to study the topological insulating behavior (Chithra H. Sharma)
Publications
- Physical vapor deposition-free scalable high-efficiency electrical contacts to MoS2.
Anusha Shanmugam, Muhammad Arshad Thekke Purayil, Sai Abhishikth Dhurjati and Madhu Thalakulam [link]
- Polymorphism-driven Distinct Nanomechanical, Optical, Photophysical, and Conducting Properties in a Benzothiophene-quinoline.
K. S. Bejoymohandas, Ashish Redhu, Chithra H. Sharma, Sunil SeethaLekshmi, I. S. Divya, M. S. R. N. Kiran, Madhu Thalakulam, Filippo Monti, Rajesh V. Nair, Sunil Varughese [link]
- Transient vortex dynamics and evolution of Bose metal from a 2D superconductor on MoS2.
Sreevidya Narayanan, Anoop Kamalasanan, Annu Anns Sunny and Madhu Thalakulam [link]
- GHz operation of a quantum point contact using stub-impedance matching circuit.
Anusha Shanmugam, Prasanta Kumbhakar, Harikrishnan Sundaresan, Annu Anns Sunny,J.L. Reno , Madhu Thalakulam [link]
- Dimorphs of a Benzothiophene-quinoline Derivative with Distinct Mechanical, Optical, Photophysical and Conducting Properties
KS Bejoymohandas, A Ashish, Chithra H Sharma, Sunil SeethaLekshmi, Kiran SRN Mangalampalli, Indira S Divya, Madhu Thalakulam, Filippo Monti, Rajesh V Nair, Sunil Varughese.
- Growth of highly crystalline ultrathin two-dimensional selenene
Prasad V Sarma, Renjith Nadarajan, Ritesh Kumar, Riya Mol Patinharayil, Navya Biju, Sreevidya Narayanan, Guanhui Gao, Chandra Sekhar Tiwary, Madhu Thalakulam, Rajeev N Kini, Abhishek K Singh, Pulickel M Ajayan, Manikoth M Shaijumon.
- Quantum point contact galvanically coupled to planar superconducting resonator: a shot-noise-limited broad-band electrical amplifier
Prasanta Kumbhakar, Anusha Shanmugam, Chithra H Sharma, JL Reno and, Madhu Thalakulam. [link]
- Strain Engineering the Schottky barrier and electrical transport on MoS2. [link]
Ashby J Philip, Arya Tthenapparambil and Madhu Thalakulam, Nanotechnology 31, 275703 (2020)
- Electrocatalysis on edge-rich spiral WS2 for hydrogen evolution. [link]
Prasad V. Sarma, Arijit Kayal, Chithra H. Sharma, Madhu Thalakulam, J. Mitra, M. M. Shaijumon, ACS-Nano,13, 10448 (2019)
- Quantum tunnel junction coupled with coplanar waveguide resonator. [link]
Prasanta Kumbhakar & Madhu Thalakulam, AIP Conference Proceedings 2115, 030220 (2019)
- 2D superconductivity and vortex dynamics in 1T-MoS2. [link]
Chithra H. Sharma, Ananthu P.S., Sangeeth S. Varma and Madhu Thalakulam Communications Physics, 1, 90 (2018); arXiv:1805.07060
- Stable and scalable 1T MoS2 with low-temperature coefficient of resistance. [link]
Chithra H. Sharma, Ananthu P.S., Abin Varghese and Madhu Thalakulam Scientific Reports, 8, 12463 (2018) arXiv:1801.07049
- Split-gated point-contact for electrostatic confinement of transport in MoS2/h-BN hybrid structures. [link]
Chithra H. Sharma and Madhu Thalakulam Scientific Reports, 7, 735 (2017)
- Topography preserved microwave plasma etching for top-down layer engineering in MoS2 and other van der Waals materials. [link]
Abin Varghese, Chithra H. Sharma and Madhu Thalakulam, Nanoscale, 9, 3818 (2017)
- Chaotic quantum transport near the charge neutrality point in inverted type-II InAs/GaSb field-effect transistors. [link]
W. Pan, J. F. Klem, J. K. Kim, M. Thalakulam, M. J. Cich, and S. K. Lyo, Appl. Phys. Lett., 102, 033504, (2013).
- Single-shot charge sensing and tunnel-rate spectroscopy of a few electron Si/SiGe quantum dot. [link]
Madhu Thalakulam, et al., Phys. Rev. B, 84, 045307 (2011).
- Pauli spin blockade and lifetime-enhanced transport in a Si/SiGe double quantum dot. [link]
C. B. Simmons, Teck Seng Koh, Nakul Shaji, Madhu Thalakulam, Levente J. Klein, Hua Qin, H. Luo, D. E. Savage, M. G. Lagally, A. J. Rimberg, R. Joynt, R. H. Blick, Mark Friesen, S. N. Coppersmith and, M. A. Eriksson, Phys. Rev. B, 82, 245312 (2010).
- Toward Si/SiGe quantum dot spin qubits: Gated Si/SiGe single and double quantum dots. [link]
C. B. Simmons, J. R. Prance, Madhu Thalakulam, B. M. Rosemeyer, B. J. Van Bael, D. E. Savage, M. G. Lagally, R. Joynt, M. Friesen, S. N. Coppersmith, and M. A. Eriksson, ECS Tran. 33, 639 (2010).
- A macroscopic mechanical resonator driven by mesoscopic electrical backaction. [link] J. Stettenheim, MadhuThalakulam, FengPan, Mustafa Bal, Z. Ji, W. W. Xue, LorenPfeiffer, K. W. West, and A. J. Rimberg, Nature, 466, 86 (2010).
- Fast tunnel rates in Si/SiGe one-electron single and double quantum dots. [link]
Madhu Thalakulam, C. B. Simmons, B. M. Rosemeyer, D. E. Savage, M. G. Lagally, M. Friesen, S. N. Coppersmith, and M. A. Eriksson, Appl. Phys. Lett., 96, 183104 (2010).
