Energy dependence of the quasiparticle lifetime in a 2DES

We present a novel technique for measuring the lifetime of quasiparticle excitations of a 2DES by investigating the tunnelling into a quantum dot from a 2DES over an extended range of energy from the Fermi energy to the sub-band edge. We find that the lifetime τqp, of a quasihole excitation, caused by removing an electron from a 2DES state with energy ε below the Fermi energy EF, has the form τqp=αℏ/ε, where α is a constant of order unity.