Quantum Computing

Optical qubits, coherent control of decoherence, and quantum algorithms

Optical approaches to qubits, coherent control of decoherence, and quantum algorithms using shaped femtosecond laser pulses.

Question

Can shaped femtosecond pulses implement quantum logic on molecular states while suppressing decoherence, the dephasing of quantum coherence through coupling to non-radiative channels? The lab treats coherent control and quantum information processing together; the shaped-pulse instrument is described on the research overview.

Technique

The lab’s papers consider phase-modulated femtosecond pulses acting on molecular ensembles as qubit registers. The sections below follow the sequence of the lab’s work.

Ensemble quantum computing with laser phase modulation

The 2002 Physical Review Letters paper reports selective control of decoherence in a multilevel system through the chirp of the laser pulse, and presents the result as the basis of a robustly implementable CNOT gate [1]. A companion paper treats decoherence control in quantum computing with simple chirped pulses [2], and a further article discusses ultrafast pulse shaping approaches to quantum computing, in particular the acousto-optic-modulator-based Fourier-transform pulse shaper [3].

Adiabatic quantum computing

Building on this foundation, the lab developed an adiabatic approach to optical quantum computing. The 2005 paper presents quantum logical gates for multilevel systems through decoherence control under the quantum adiabatic method, using simple phase-modulated laser pulses [4]. A 2006 paper describes how adiabatic coherent control can reduce decoherence and population loss to non-radiative channels [5]. A 2007 paper proposes a quantification of the two-level character of a multilevel system through the off-diagonal density matrix elements [6], and another 2007 paper argues that experimental demonstrations of selective population transfer by adiabatic rapid passage form useful adiabatic quantum computing logic, and presents a framework for approximate Euclidean travelling salesman problems [7].

Molecular states as qubits

The foundations for this program lie in the coherent control of multiphoton transitions with femtosecond pulse shaping, where a multiphoton density-matrix approach extends single-photon coherent control ideas to systems without a single-photon resonance [8]. The lab then proposed molecular ions and molecular states as qubits. The 2010 paper on molecular ions (femtosecond control of molecular fragmentation with multiple knobs) [9] and the 2011 paper “Towards Using Molecular States as Qubits” [10] discuss molecular systems as possible qubits. The 2011 paper explores the non-resonant fragmentation of n-propyl benzene as a model case and reports that chirp and polarization act independently, which makes them candidate “logic” parameters. The approach is all-optical.

Recent directions

More recent work treats quantum distributed computing with shaped laser pulses and quantum algorithms [11,12,13].

Representative papers

Laser Phase Modulation Approaches towards Ensemble Quantum Computing, Physical Review Letters, 2002. doi:10/c339br
Adiabatic Quantum Computing with Phase Modulated Laser Pulses, Journal of Physics A, 2005. doi:10/cf95fb
Towards Using Molecular States as Qubits, AIP Conference Proceedings, 2011. doi:10/bfnp4m

Full list of papers here.

Publications

Quantum Distributed Computing with Shaped Laser Pulses. R. Goswami and D. Goswami, in 13th International Conference on Fiber Optics and Photonics (OSA, 2016), p. W4C.3

BibTeX: @inproceedings{goswamiQuantumDistributedComputing2016,
  title = {Quantum {{Distributed Computing}} with {{Shaped Laser Pulses}}},
  booktitle = {13th {{International Conference}} on {{Fiber Optics}} and {{Photonics}}},
  author = {Goswami, Rohit and Goswami, Debabrata},
  year = {2016},
  pages = {W4C.3},
  publisher = {OSA},
  address = {Kanpur},
  doi = {10/gf5mrr},
  urldate = {2019-08-01},
  copyright = {All rights reserved},
  isbn = {978-1-943580-22-4},
  langid = {english},
  annotation = {GSCC: 0000183 \\
  2 citations (Crossref) [2024-05-28]\\
  00000}
}

Quantum Distributed Computing Applied to Grover’s Search Algorithm. D. Goswami, in Computing with New Resources: Essays Dedicated to Jozef Gruska on the Occasion of His 80th Birthday, C. S. Calude, R. Freivalds, and I. Kazuo, eds., Lecture Notes in Computer Science (Springer International Publishing, 2014), pp. 192–199

BibTeX: @incollection{goswamiQuantumDistributedComputing2014,
  title = {Quantum {{Distributed Computing Applied}} to {{Grover}}'s {{Search Algorithm}}},
  booktitle = {Computing with {{New Resources}}: {{Essays Dedicated}} to {{Jozef Gruska}} on the {{Occasion}} of {{His}} 80th {{Birthday}}},
  author = {Goswami, Debabrata},
  editor = {Calude, Cristian S. and Freivalds, R{\=u}si{\c n}{\v s} and Kazuo, Iwama},
  year = {2014},
  series = {Lecture {{Notes}} in {{Computer Science}}},
  pages = {192--199},
  publisher = {Springer International Publishing},
  address = {Cham},
  urldate = {2019-08-02},
  isbn = {978-3-319-13350-8},
  langid = {english},
  annotation = {GSCC: 0000004 \\
  00000 \\
  10.1007/978-3-319-13350-8\_14}
}

Quantum Algorithm to Solve a Maze: Converting the Maze Problem into a Search Problem. N. Kumar and D. Goswami, arXiv:1312.4116 [quant-ph] (2013)

BibTeX: @article{kumarQuantumAlgorithmSolve2013,
  title = {Quantum {{Algorithm}} to {{Solve}} a {{Maze}}: {{Converting}} the {{Maze Problem}} into a {{Search Problem}}},
  shorttitle = {Quantum {{Algorithm}} to {{Solve}} a {{Maze}}},
  author = {Kumar, Niraj and Goswami, Debabrata},
  year = {2013},
  month = dec,
  journal = {arXiv:1312.4116 [quant-ph]},
  eprint = {1312.4116},
  primaryclass = {quant-ph},
  urldate = {2019-08-02},
  archiveprefix = {arXiv},
  annotation = {GSCC: 0000007 \\
  00000}
}

Towards Using Molecular States as Qubits. D. Goswami, T. Goswami, S. K. K. Kumar, and D. K. Das, AIP Conference Proceedings 1384(1), 251–253 (2011)

BibTeX: @article{goswamiUsingMolecularStates2011,
  title = {Towards {{Using Molecular States}} as {{Qubits}}},
  author = {Goswami, Debabrata and Goswami, Tapas and Kumar, S. K. Karthick and Das, Dipak K.},
  year = {2011},
  month = sep,
  journal = {AIP Conference Proceedings},
  volume = {1384},
  number = {1},
  pages = {251--253},
  issn = {0094-243X},
  doi = {10/bfnp4m},
  urldate = {2019-08-02},
  annotation = {GSCC: 0000000 \\
  0 citations (Crossref) [2024-05-28]\\
  00000}
}

Towards Using Molecular Ions as Qubits: Femtosecond Control of Molecular Fragmentation with Multiple Knobs. T. Goswami, D. K. Das, and D. Goswami, Pramana 75(6), 1065–1069 (2010)

BibTeX: @article{goswamiUsingMolecularIons2010,
  title = {Towards Using Molecular Ions as Qubits: {{Femtosecond}} Control of Molecular Fragmentation with Multiple Knobs},
  shorttitle = {Towards Using Molecular Ions as Qubits},
  author = {Goswami, Tapas and Das, Dipak K. and Goswami, Debabrata},
  year = {2010},
  month = dec,
  journal = {Pramana},
  volume = {75},
  number = {6},
  pages = {1065--1069},
  issn = {0973-7111},
  doi = {10/cf945s},
  urldate = {2019-08-14},
  langid = {english},
  annotation = {GSCC: 0000000 \\
  0 citations (Crossref) [2024-05-28]\\
  00000}
}

Probing Coherence Aspects of Adiabatic Quantum Computation and Control. D. Goswami, The Journal of Chemical Physics 127(12), 124305 (2007)

BibTeX: @article{goswamiProbingCoherenceAspects2007,
  title = {Probing Coherence Aspects of Adiabatic Quantum Computation and Control},
  author = {Goswami, Debabrata},
  year = {2007},
  month = sep,
  journal = {The Journal of Chemical Physics},
  volume = {127},
  number = {12},
  pages = {124305},
  issn = {0021-9606},
  doi = {10.1063/1.2768954},
  urldate = {2019-08-14},
  annotation = {GSCC: 0000005 \\
  4 citations (Crossref) [2024-05-28]\\
  00005}
}

On the Practicality of Adiabatic Quantum Computing with Optical Schemes. D. Goswami, International Journal of Quantum Information 05(01n02), 179–188 (2007)

BibTeX: @article{goswamiPracticalityAdiabaticQuantum2007,
  title = {On the Practicality of Adiabatic Quantum Computing with Optical Schemes},
  author = {Goswami, Debabrata},
  year = {2007},
  month = feb,
  journal = {International Journal of Quantum Information},
  volume = {05},
  number = {01n02},
  pages = {179--188},
  issn = {0219-7499},
  doi = {10/fkvv3x},
  urldate = {2019-08-14},
  annotation = {GSCC: 0000003 \\
  2 citations (Crossref) [2024-05-28]}
}

Adiabatic Quantum Computation: Coherent Control Back Action. D. Goswami, AIP Conference Proceedings 864(1), 273–294 (2006)

BibTeX: @article{goswamiAdiabaticQuantumComputation2006,
  title = {Adiabatic {{Quantum Computation}}: {{Coherent Control Back Action}}},
  shorttitle = {Adiabatic {{Quantum Computation}}},
  author = {Goswami, Debabrata},
  year = {2006},
  month = nov,
  journal = {AIP Conference Proceedings},
  volume = {864},
  number = {1},
  pages = {273--294},
  issn = {0094-243X},
  doi = {10/dg98nw},
  urldate = {2019-08-14},
  annotation = {GSCC: 0000002 \\
  0 citations (Crossref) [2024-05-28]\\
  00002}
}

Adiabatic Quantum Computing with Phase Modulated Laser Pulses. D. Goswami, Journal of Physics A: Mathematical and General 38(38), L615–L626 (2005)

BibTeX: @article{goswamiAdiabaticQuantumComputing2005,
  title = {Adiabatic Quantum Computing with Phase Modulated Laser Pulses},
  author = {Goswami, Debabrata},
  year = {2005},
  month = sep,
  journal = {Journal of Physics A: Mathematical and General},
  volume = {38},
  number = {38},
  pages = {L615-L626},
  issn = {0305-4470, 1361-6447},
  doi = {10/cf95fb},
  urldate = {2019-08-14},
  langid = {english},
  annotation = {GSCC: 0000010 \\
  7 citations (Crossref) [2024-05-28]\\
  00008}
}

Ultrafast Pulse Shaping Approaches to Quantum Computing. D. Goswami, arXiv:quant-ph/0312192 (2003)

BibTeX: @article{goswamiUltrafastPulseShaping2003,
  title = {Ultrafast {{Pulse Shaping Approaches}} to {{Quantum Computing}}},
  author = {Goswami, Debabrata},
  year = {2003},
  month = dec,
  journal = {arXiv:quant-ph/0312192},
  eprint = {quant-ph/0312192},
  urldate = {2019-08-14},
  archiveprefix = {arXiv},
  annotation = {GSCC: 0000018 \\
  00017}
}

Decoherence Control in Quantum Computing with Simple Chirped Pulses. D. Goswami, Pramana 59(2), 235–242 (2002)

BibTeX: @article{goswamiDecoherenceControlQuantum2002,
  title = {Decoherence Control in Quantum Computing with Simple Chirped Pulses},
  author = {Goswami, Debabrata},
  year = {2002},
  month = aug,
  journal = {Pramana},
  volume = {59},
  number = {2},
  pages = {235--242},
  issn = {0973-7111},
  doi = {10/bv363m},
  urldate = {2019-08-14},
  langid = {english},
  annotation = {GSCC: 0000001 \\
  0 citations (Crossref) [2024-05-28]\\
  00000}
}

Laser Phase Modulation Approaches towards Ensemble Quantum Computing. D. Goswami, Physical Review Letters 88(17), 177901 (2002)

BibTeX: @article{goswamiLaserPhaseModulation2002,
  title = {Laser {{Phase Modulation Approaches}} towards {{Ensemble Quantum Computing}}},
  author = {Goswami, Debabrata},
  year = {2002},
  month = apr,
  journal = {Physical Review Letters},
  volume = {88},
  number = {17},
  pages = {177901},
  doi = {10/c339br},
  urldate = {2019-08-14},
  annotation = {GSCC: 0000040 \\
  22 citations (Crossref) [2024-05-28]\\
  00000}
}

Coherent Control of Multiphoton Transitions with Femtosecond Pulse Shaping. S. A. Hosseini and D. Goswami, Physical Review A 64(3), 033410 (2001)

BibTeX: @article{hosseiniCoherentControlMultiphoton2001,
  title = {Coherent Control of Multiphoton Transitions with Femtosecond Pulse Shaping},
  author = {Hosseini, S. Abbas and Goswami, Debabrata},
  year = {2001},
  month = aug,
  journal = {Physical Review A},
  volume = {64},
  number = {3},
  pages = {033410},
  doi = {10/ffjx3v},
  urldate = {2019-08-14},
  annotation = {GSCC: 0000066 \\
  31 citations (Crossref) [2024-05-28]\\
  00000}
}