Two-channel Kondo physics in tunnel-coupled double quantum dots

Abstract

We investigate theoretically the possibility of observing two-channel Kondo (2CK) physics in tunnel-coupled double quantum dots (TCDQDs), at both zero and finite magnetic fields; taking the two-impurity Anderson model (2AIM) as the basic TCDQD model, together with effective low-energy models arising from it by Schrieffer-Wolff transformations to second and third order in the tunnel couplings. The models are studied primarily using Wilson's numerical renormalization group. At zero-field our basic conclusion is that while 2CK physics arises in principle provided the system is sufficiently strongly-correlated, the temperature window over which it could be observed is much lower than is experimentally feasible. This finding disagrees with recent work on the problem, and we explain why. At finite field, we show that the quantum phase transition known to arise at zero-field in the two-impurity Kondo model (2IKM), with an essentially 2CK quantum critical point, persists at finite fields. This raises the prospect of access to 2CK physics by tuning a magnetic field, although preliminary investigation suggests this to be even less feasible than at zero field.

10 pages, 8 figures. Version as published in PRB

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• Tunable Kondo physics in a carbon nanotube double quantum dot
• Multiple magnetic impurities on surfaces: Scattering and quasiparticle interference
• Effective low-energy description of the two impurity Anderson model: RKKY interaction and quantum criticality
• Supersymmetric approach to heavy fermion systems
• Convergence of energy scales on the approach to a local quantum critical point
• A thermally driven out-of-equilibrium two-impurity Kondo system
• Kondo temperature and screening extension in a double dot system
• Rescuing a Quantum Phase Transition with Quantum Noise
• Spin current Kondo effect in frustrated Kondo systems
• Driving XXZ spin chains: Magnetic-field and boundary effects
• Kondo Screening and Indirect Magnetic Exchange through a Conventional Superconductor Studied by the Density-Matrix Renormalization Group