Submitted
 Spinorbit interaction and anomalous spin relaxation in carbon nanotube quantum dots
Denis V. Bulaev,
B. Trauzettel, Daniel Loss,
arXiv:0712.3767v1 [condmat.meshall].
We study spin relaxation and decoherence caused by electronlattice and
spinorbit interaction and predict striking effects induced by magnetic fields
B. For particular values
of B, destructive interference occurs resulting in ultralong spin
relaxation times T_{1} exceeding tens of seconds. For small phonon frequencies ω, we find a
1/√ω spinphonon noise spectrum 
a novel dissipation channel for spins in quantum dots  which can reduce
T_{1} by many orders of magnitude. We show that
nanotubes exhibit zerofield level splitting caused by spinorbit
interaction. This enables an allelectrical and phasecoherent control of
spin.
2008
 Electron and hole spin dynamics and decoherence in quantum dots
D. Klauser, D. V. Bulaev, W. A. Coish, Daniel Loss,
Chapter 10 in Semiconductor Quantum Bits, eds. O. Benson and F. Henneberger, World Scientific, 2008.
ISBN 9789814241052
arXiv:0706.1514v1 [condmat.meshall]
We review our work on the dynamics and decoherence of electron and hole spins in single and double quantum dots. The first part, on electron spins, focuses on decoherence induced via the hyperfine interaction while the second part covers decoherence and relaxation of heavyhole spins due to spinorbit interaction as well as the manipulation of heavyhole spin using electric dipole spin resonance.
2007
 Observation of extremely slow hole spin relaxation in selfassembled quantum dots
D. Heiss, S. Schaeck, H. Huebl, M. Bichler, G. Abstreiter, J. J. Finley, D. V. Bulaev, Daniel Loss,
Phys. Rev. B 76, 241306(R) (2007); arXiv:0705.1466v2 [condmat.meshall].
We report the measurement of extremely slow hole spin relaxation dynamics in selfassembled InGaAs quantum dots. Individual spin orientated holes are optically created in the lowest orbital state of each dot and read out after a defined storage time using spin memory devices. The hole spin relaxation time (T_1h) is measured as a function of the external magnetic field and lattice temperature. As predicted by theory, hole spin relaxation can occur over remarkably long timescales in strongly confined quantum dots (up to T_1h ~270 \mus) comparable to the corresponding time for electrons. Our findings are supported by calculations that reproduce both the observed magnetic field and temperature dependencies. The results show that hole spin relaxation in strongly confined quantum dots is governed by spinlattice interaction, in marked contrast to higher dimensional nanostructures where it is limited by spinorbit coupling between valence bands.

Spin qubits in graphene quantum dots
B. Trauzettel, Denis V. Bulaev, Daniel Loss, Guido Burkard,
Nature Physics 3, 192 (2007); News and Views; Research Highlights; condmat/0611252.
We propose how to form spin qubits in graphene. A crucial requirement to achieve this goal is to find quantum dot states where the usual valley degeneracy in bulk graphene is lifted. We show that this problem can be avoided in quantum dots based on ribbons of graphene with semiconducting armchair boundaries. For such a setup, we find the energies and the exact wave functions of bound states, which are required for localized qubits. Additionally, we show that spin qubits in graphene can not only be coupled between nearest neighbor quantum dots via Heisenberg exchange interaction but also over long distances. This remarkable feature is a direct consequence of the quasirelativistic spectrum of graphene.
 Electric Dipole Spin Resonance for Heavy Holes in Quantum Dots
Denis V. Bulaev, Daniel Loss,
Phys. Rev. Lett. 98, 097202 (2007);
condmat/0608410.
We propose and analyze a new method for manipulation of a heavy hole spin in a quantum dot. Due to spinorbit coupling between states with different orbital momenta and opposite spin orientations, an applied rf electric field induces transitions between spinup and spindown states. This scheme can be used for detection of heavyhole spin resonance signals, for the control of the spin dynamics in twodimensional systems, and for determining important parameters of heavyholes such as the effective gfactor, mass, spinorbit coupling constants, spin relaxation and decoherence times.
2005

Spin Relaxation and Decoherence of Holes in Quantum Dots
Denis V. Bulaev, Daniel Loss,
Phys. Rev. Lett. 95, 076805 (2005);
condmat/0503181.
We investigate heavyhole spin relaxation and decoherence in quantum dots in perpendicular magnetic fields. We show that at low temperatures the spin decoherence time is two times longer than the spin relaxation time. We find that the spin relaxation time for heavy holes can be comparable to or even longer than that for electrons in strongly twodimensional quantum dots. We discuss the difference in the magneticfield dependence of the spin relaxation rate due to Rashba or Dresselhaus spinorbit coupling for systems with positive (i.e., GaAs quantum dots) or negative (i.e., InAs quantum dots) $g$factor.
 Spin relaxation and anticrossing in quantum dots: Rashba versus Dresselhaus spinorbit coupling
Denis V. Bulaev, Daniel Loss,
Phys. Rev. B 71, 205324 (2005);
condmat/0409614.
The spinorbit splitting of the electron levels in a twodimensional quantum dot in a perpendicular magnetic field is studied. It is shown that at the point of an accidental degeneracy of the two lowest levels above the ground state the Rashba spinorbit coupling leads to a level anticrossing and to mixing of spinup and spindown states, whereas there is no mixing of these levels due to the Dresselhaus term. We calculate the relaxation and decoherence times of the three lowest levels due to phonons. We find that the spin relaxation rate as a function of a magnetic field exhibits a cusplike structure for Rashba but not for Dresselhaus spinorbit interaction.
2004

Effect of surface curvature on magnetic moment and persistent currents in twodimensional quantum rings and
dots.
D.V. Bulaev, V.A. Geyler, V.A. Margulis,
Phys. Rev. B 69, 195313 (2004); condmat/0308500,
2003
 Magnetic moment of an electron gas on the surface of
constant negative curvature
D.V. Bulaev, V.A. Margulis,
Eur. Phys. J. B 36, 183186 (2003); condmat/0307401
 Quantum Hall effect on the Lobachevsky plane
D.V. Bulaev, V.A. Geyler, V.A. Margulis,
Physica B 337, 180185 (2003); condmat/0305086
 Magnetic moment of a twodimensional quantum ring on the
surface of constant negative curvature (in Russian)
D.V. Bulaev, V.A. Margulis,
Izv. VUZov. Povolzhskii reg. Est. nauki. No.2, 133140 (2003)
 Electrodynamic response of a nanosphere placed in a magnetic field
D.V. Bulaev, V.A. Margulis,
Fiz. Tverd. Tela 45, 349358 (2003) [Sov. Phys. Solid State 45, 369380 (2003)]
2002
 Absorption of Electromagnetic Radiation by Electrons of a Nanosphere
D.V. Bulaev, V.A. Margulis,
Fiz. Tverd. Tela 44, 15571567 (2002)
[Sov. Phys. Solid State 44, 16321642 (2002)]
 Electrodynamic Response of a Nanosphere
D.V. Bulaev, V.A. Geyler, V.A. Margulis,
Fiz. Tverd. Tela 44, 471472 (2002)
[Sov. Phys. Solid State 44, 490492 (2002)]
2000
 Magnetic response for an ellipsoid of revolution in a magnetic field
D.V. Bulaev, V.A. Geyler, V.A. Margulis,
Phys. Rev. B 62, 1151711526 (2000)
Theses
PhD Thesis
 Magnetic and Electrodynamic Response of Nonplanar Nanostructures (in Russian)
D.V. Bulaev,
Dissertation (Mordovian State University, 2003)
Diploma Thesis
 Magnetic Response of a Quantum Ellipsoid of Revolution (in Russian)
D.V. Bulaev,
Diploma work (Mordovian State University, 2000)