Measurement of 1- Qubit Opera4ons on Single Photons

Transcription

1 Measurement of 1- Qubit Opera4ons on Single Photons Daniel Urrego, Víctor Mahecha, David Guzmán Physics Department and Quantum Op4cs Laboratory Universidad de Los Andes, Bogota, Colombia Interna4onal workshop on quantum coherence & decoherence September 27 th, 2012 Cali, Colombia h"p://fc07.deviantart.net/fs70/f/2010/310/b/f/blue_laser_texture_7_by_creepiest- d329eb4.jpg 1

2 Content Mo4va4on Theore4cal background. Wave plate. Quarter wave plate. Half wave plate. Experimental setup Source Measurement Boxes Process Results. Quarter Wave plate Horizontal and verncal basis Diagonal and ann- diagonal basis Circular basis. Half Wave plate Horizontal and verncal basis Diagonal and ann- diagonal basis Circular basis. Conclusions. Bibliography. 2

3 Mo4va4on When speaking of quantum informanon and quantum compunng we find serious or gate applicanons. Now this experiment seeks to move from the theorencal to the experimental, and being an introducnon to the propernes of the gates experimentally. Example Hadamard gate Half wave plate 22.5 degrees 3

4 Wave plate Or retarder is an experimental device with two refracnve index difference, which is able to delay a polarizanon components of incident photons. ψ 1 > WP ψ 2 > 4

5 Theore4cal background Wave Plates Quarter wave plate A λ/4 =[ 1&0@0& i ] A λ 4 (θ)=r(θ) A λ 4 R 1 (θ) 5

6 Theore4cal background Wave Plates Half wave plate A λ/2 =[ 1&0@0& 1 ] 6

7 Experimental Setup Experimental Setup Source Opera4on Quarter wave plate Half wave plate Measurement Boxes Laser BBO Type I 7

8 Experimental Setup Source Laser 405nm of 50mW Photons s βbo type I. 8 x 10 4 Photons s 0.6 % are detected at the same /me. Produced photons: horizontally polarized Signal photon announces existence of idler photon (heralded single photon source) 8

9 Experimental Setup Experimental Setup Source Opera4on Quarter wave plate Half wave plate Measurement Boxes Wave plates Polariza4on Beam Spli]er Silicon Detectors - Single Photon CounNng Module. 9

10 Experimental Setup Measurement Boxes Horizontal / verncal basis Diagonal / ann diagonal basis Right circular / led circular basis 10

11 Experimental Setup Experimental Setup Source Opera4on Quarter wave plate Half wave plate Measurement Boxes For the HWP 17 different angles For QWP 9 different angles 3 minutes of data for each angle Detector s window is of 0.5s 11

12 Experimental Setup Process Source OperaNon Measurement Box. Pump Idler Signal 12

13 Results Horizontal / verncal basis - QWP Experimental theorencal Horizontal P H = ((1 i)cos^ 2 (θ) Sin ^ 2 ( VerNcal P V = (Cos^ 2 (θ)+i Sin ^ 2 ( 13

14 Results Diagonal / ann diagonal basis - QWP AnN- diagonal P A = ( (1+i) cos (θ) Sin(θ)/ 2 + Cos 2 (θ) i Sin 2 ( 2 ) 2 Diagonal P D = ( (1+i) cos (θ) Sin(θ) / 2 + Cos 2 (θ) i Sin 2 ) 2 14

15 Results Circular basis QWP Right circular P R = ( (1 i) cos (θ) Sin(θ) / 2 + Cos 2 (θ) i Sin 2 (θ)/ 2 ) 2 P L = ( (1 i) cos (θ) Sin(θ) / 2 + Cos 2 (θ) i Sin 2 (θ)/ Led circular 2 ) 2 15

16 Results Horizontal / verncal basis HWP Horizontal P H =Cos ^ 2 2θ VerNcal P V =Sin ^ 2 2θ 16

17 Results Diagonal / ann diagonal basis HWP AnN- Diagonal P A = ( Cos(2θ)/ 2 Sin(2θ)/ Diagonal P D = ( Cos(2θ)/ 2 + Sin(2θ)/ 17

18 Results Circular basis HWP Led circular P L = ( Cos(2θ)/ 2 i Sin(2θ)/ Right circular P R = ( Cos(2θ)/ 2 +i Sin(2θ)/ 18

19 Conclusions The data obtained during the process are theorencally expected which proves operanons with qubits in a purely experimental process and shows the characterisncs of each operanon. It serves to understand superposinon and normalizanon concepts on qubits. Results show an addinonal phase compared with theorencal values, due to the alignment of the different wave plates. Therefore it is necessary to improve alignment methods. Today this setup is being used by students of a quantum opncs course (Universidad de Los Andes), as a regular laboratory session. 19

20 Bibliography B. E. A. Saleh, M. C. Teich, Fundamentals of photonics (John wiley & Sons, Inc., New York, 1991). G. Jaeger, Entanglement, informa4on, and the interpreta4on of quantum mechanics (Springer, Boston, 2009). M. A. Nielsen, I. L. Chuang, Quantum computa4on and quantum informa4on (Cambridge U. P., Cambridge, 2008). P. Bronner, A. Strunz, C. Silberhorn and J. Meyn. Interac/ve Screen experiments with single photons. (Eur. J. Phys 30 (2009) ). E. Galvez. Qubit quantum mechanics with correlated- photon experiments. (Departement of Physics and Asstronomy, Colgate University) B. Pearson and P. Jackson. A hands- on introduc/on to single photons and quantum mechanics for undergraduates. (Departement of Physics and Asstronomy, Dickinson College) 20