Use this URL to cite or link to this record in EThOS:
Title: Signatures of charge noise and its impact on exciton qubits
Author: Purohit, Vishal
ISNI:       0000 0004 6422 3561
Awarding Body: University of St Andrews
Current Institution: University of St Andrews
Date of Award: 2016
Availability of Full Text:
Access from EThOS:
Access from Institution:
The research contained within this thesis concerns the detection, identification and effect of charge noise on quantum dot systems. In the first research chapter we study the cross correlation between pairs of exciton qubits subject to a common fluctuating charge environment, whose dynamics are solved using a transfer matrix approach. Our results show that we are able to discern features showing whether or not the charges interact with both quantum dots simultaneously i.e., form a correlated noise source. We find that qubits in a common charge environment display photon bunching, if both dots are driven on resonance or if the laser detunings are equal in both qubits and anitibunching if the laser detunings are in opposite directions. In the second research chapter we study the auto-correlation function of a single optically driven exciton qubit interacting with an environment consisting of 1/f noise and a fluctuating charge. We again use the transfer matrix method and a sum of Lorentzian distributions to approximate 1/f noise. Our simulations show that signatures of 1/f noise do exist in photon correlation measurements. From such measurements we are also able to determine a minimum cut-off frequency of the 1/f noise, in the case that there is such a cut-off. In addition we also show that a 1/f and a single fluctuator can be distinguished using the auto-correlation. In the final research chapter we study a pair of quantum dots, each with a low lying electron spin qubit and one higher lying level that can be selectively optically excited from one of the two spin states. Entanglement between the two spins can be achieved through path erasure. We look at the effect of a single fluctuating charge of the entanglement between these two `L' shaped electronic structures.
Supervisor: Lovett, Brendon W. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC611.6Q35P8 ; Quantum dots ; Coherence (Nuclear physics) ; Quantum theory