SUPERCONDUCTING PHASE TUNED SAMPLE-SPECIFIC CONDUCTANCE FLUCTUATIONS

We have studied sample-specific conductance fluctuations tuned by the phase difference between superconducting boundaries attached to a T-sh aped two-dimensional electron gas. In low magnetic fields, oscillation s due to phase-conjugated Andreev reflections were observed with an am plitude delta G(qp)similar or equal to 0.10e(2)/h. These oscillations were suppressed by a flux of approximately h/e through the interferenc e region. For larger magnetic fields, superconducting-phase modulated sample-specific conductance fluctuations were found with an amplitude delta Gy(Delta phi)similar or equal to.0.005e(2)/h.