BIDIRECTIONAL SHOT-NOISE IN A SINGLY OCCUPIED CHANNEL

We calculate the power spectrum of the noisy current in a narrow chann el that admits one charge carrier at a time from the left L or right R reservoirs. The random positive and negative currents are produced by the random arrival and departure of discrete charges ata measuring de vice on one side. The unidirectional currents are: not independent bec ause the presence of one charge in the channel blocks the entrance of another. Four classes of trajectories are possible: the trans trajecto ries LR and RL and cis trajectories LL and RR. The power spectrum of t he total current is described by explicit formulas, depending only on the statistics of the interarrival times and times spent in the channe l. These formulas generalize those of shot (e.g., Schottky) noise and predict more complex behavior than the sum of the noises of the four t ypes of trajectories, if they were independent: (i) the mean current a nd the intensity of fluctuations saturate as the arrival time on one s ide decreases and (ii) the noise intensity depends nonlinearly on the mean net current. Explicit formulas are given and special cases are an alyzed.