integrated devices for quantum information with polarization qubits · 2017-03-14 · integrated...
TRANSCRIPT
Linda Sansoni
Integrated devicesfor quantum informationwith polarization qubits
http:\\quantumoptics.phys.uniroma1.it
Seminario di dottorato XXV ciclo
20 Giugno 2011
Integrated devices for quantumInformation with polarization qubits
Collaboration with Politecnico di Milano and Istituto di Fotonica e Nanotecnologie - CNR
L. SansoniI. BongioanniG. ValloneF. SciarrinoP. Mataloni
A. CrespiR. RamponiR. Osellame
From classical to quantum...
From classical to quantum...
➩ Faster computation➩ Less resources➩ Improvement of security
Why quantum information?Why quantum information?
From classical to quantum...
➩ Faster computation➩ Less resources➩ Improvement of security
Why quantum information?Why quantum information?
A possible implementation is quantum optics
Single photons are used as physical systems for information transport
The information is represented by one of the degrees of freedom of the photons: polarization, linear momentum, orbital
angular momentum, time/energy
Building blocksClassical computation
IDENTITY
1 → 1
0 → 0
NOT 0 → 1
1 → 0
OR
A,B → A x BAND
Building blocksClassical computation Quantum computation
IDENTITY
1 → 1
0 → 0
NOT 0 → 1
1 → 0
OR
A,B → A x BAND
IDENTITY
HADAMARD
Controlled-NOT
1-2 cm
From bulk to integrated optics
Small physical size
High stability
Easy to move outside the laboratory
Large physical size
Limited stability
Difficulty to move towards applications outside laboratory
CNOT gatePoliti et al.
Science (2008)
HOM effectMarshall et al.
Optics Express (2009)
Phase controlSmith et al.
Optics Express (2009)
Integrated waveguide technology
All the experiments realized with path encoded qubits
Integrated photonics:First experiments....
Photonic quantum technologies: a promising experimental platform for quantum information processing
Why the polarization encodingPolarization:Polarization:
direction of oscillationof the e.m. field
Why the polarization encodingPolarization:Polarization:
direction of oscillationof the e.m. field
kB
kA UVpump
∣0 ⟩∣1 ⟩ ∣H ⟩∣V ⟩
Easy to manipulate: Waveplates and Polarizing Beam Splitters (PBSs)Easy to generate entangled states: Nonlinear crystals
- Quantum non-locality tests
- Quantum cryptography
- Quantum teleportation
- Quantum metrology
- Quantum computation
- Simulation
Manyapplications:
➢Femtosecond pulse tightly focused in a glass
➢Combination of multiphoton absorption and avalanche ionization induces permanent and localized refractive index increase in transparent materials
➢Waveguides fabricated in the substrate bulk by sample translation along the desired path at constant velocity with respect to the laser beam
What about polarization encoding?Laser writing technique used to realize devices able to
transmit polarization qubits
Femtosecond laser writing
L. Sansoni et al. Phys. Rev. Lett. 105, 200503 (2010)
Femtosecond laser writing
Circular waveguide
transverse profile
Characteristics:
Propagation of circular gaussian modes
Rapid device prototyping:writing speed =4 cm/s
3-dimensional capabilities
SUITABLE TO SUPPORT ANY POLARIZATION STATE
Lowbirefringence
L
Single photons
Hadamard: Integrated Beam Splitter
L
Single photons
LL
Two-photon states
Symmetric states: Triplet Antisymmetric state: Singlet
Hadamard: Integrated Beam Splitter
M. Lobino & J.L. O'Brien News &Views Nature (2011)
Polarization entanglement on a chip
L. Sansoni et al. Phys. Rev. Lett. 105, 200503 (2010)
Entanglement filter
L. Sansoni et al. Phys. Rev. Lett. 105, 200503 (2010)
Integrated CNOT gate
CNOTCNOTC C
T T
Two-qubit gate
Integrated CNOT gate
CNOTCNOTC C
T T
Two-qubit gate
Optical implementation for polarization encoded qubits
Partial PBS!
Kiesel, et al, Phys. Rev. Lett. 95, 210505 (2005).Okamoto, et al, Phys. Rev. Lett. 95, 210506 (2005).Langford, et al, Phys. Rev. Lett. 95, 210504 (2005).
Integrated CNOT gate
CNOTCNOTC C
T T
Two-qubit gate
Optical implementation for polarization encoded qubits
Transmission
Interaction length (mm)
L
Partial PBS!
Kiesel, et al, Phys. Rev. Lett. 95, 210505 (2005).Okamoto, et al, Phys. Rev. Lett. 95, 210506 (2005).Langford, et al, Phys. Rev. Lett. 95, 210504 (2005).
CNOT gate for polarization qubit
PPDC1TH = 0
TV = 2/3
PPDC2 - PPDC3TH = 1/3TV = 1
p = 1/9
CNOT gate for polarization qubit
A. Crespi, R. Ramponi, R. Osellame, L. Sansoni, I. Bongioanni, F. Sciarrino, G. Vallone, P. Mataloni, submitted
Truth table of the CNOT
Fmeasured = 0.940 ± 0.004. Festimated = 0.970 ± 0.008.
partial distinguishability of the two photons
Fexpected = 0.975 ± 0.007.device's parameters
Quantum process tomography of the CNOT gate
A. Crespi, R. Ramponi, R. Osellame, L. Sansoni, I. Bongioanni, F. Sciarrino, G. Vallone, P. Mataloni, submittedI. Bongioanni, L. Sansoni, F. Sciarrino, G. Vallone, P. Mataloni, Phys. Rev. A 82, 042307 (2010)
Beam splitter able to support polarization encoded qubit
Polarization sensitive devices
Integrated CNOT for polarization qubits
NEXT STEPS:
Tunable integrated waveplates
Hybrid manipulation of path and polarization for quantum information processing and non-locality tests
Conclusions and perspectives
L. Sansoni et al. Phys. Rev. Lett. 105, 200503 (2010)
A. Crespi, et al., arXiv: 1106.1454, submitted to Nature Photonics