Research interests and activities:

Nonequilibrium, soft-matter and biological physics

Recent publications and preprints

2024

• Bulk condensation by an active interface, Raushan Kant, Rahul Kumar Gupta, Harsh Soni, A K Sood, Sriram Ramaswamy, arXiv:2403.18329; Phys Rev Lett 133, 208301 (2024)
• Emergence of planar cell polarity from the interplay of local interactions and global gradients, Divyoj Singh, Sriram Ramaswamy, Mohit Kumar Jolly, Mohd. Suhail Rizvi, bioRxiv:2021.11.30.468750, eLife 13:e84053 (2024)
• Chirality and odd mechanics in active columnar phases, S J Kole, Gareth P Alexander, Ananyo Maitra, Sriram Ramaswamy, arXiv:2404.19514 (expands and replaces arXiv:2306.03695); PNAS Nexus 3, pgae398 (2024)
• The Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids, Thibaut Arnoulx de Pirey, Yariv Kafri, Sriram Ramaswamy, arXiv:2402.12996; Phys Rev X 14, 041034 (2024)
• Inertia drives concentration-wave turbulence in swimmer suspensions, Purnima Jain, Navdeep Rana, Sriram Ramaswamy, Prasad Perlekar, arXiv:2401.11927; Phys. Rev. Lett. 133, 158302 (2024)
• Defect turbulence in a dense suspension of polar, active swimmers, N Rana, R Chatterjee, S Ro, D Levine, S Ramaswamy, P Perlekar, Phys. Rev. E 109, 024603 (2024) arXiv:2305.15197

  2023

• Emergent hydrodynamics in a non-reciprocal classical isotropic magnet, Nisarg Bhatt, Subroto Mukerjee, Sriram Ramaswamy, arXiv:2312.16500
• Active Caustics, Rahul Chajwa, Rajarshi, Sriram Ramaswamy, Rama Govindarajan, arXiv:2310.01829
• Dynamics of Ordered Active Columns: Flows, Twists, and Waves, S. J. Kole, G P Alexander, A Maitra, S Ramaswamy, arXiv:2306.03695

  2022

• Robust Molecular Computation by Active Mechanics, Kabir Husain, Sriram Ramaswamy, Madan Rao (arXiv:2204.04838)
• Symmetry, Thermodynamics and Topology in Active Matter, M J Bowick, N Fakhri, M C Marchetti, S Ramaswamy, Phys. Rev. X 12, 010501 (2022); arXiv:2107.00724
• Two-temperature activity induces liquid-crystal phases inaccessible in equilibrium, Jayeeta Chattopadhyay, Sriram Ramaswamy, Chandan Dasgupta, Prabal K. Maiti, arXiv:2205.00667; Phys. Rev. E 107, 024701 (2023)
• Active nonreciprocal attraction between motile particles in an elastic medium, Rahul Kumar Gupta, Raushan Kant, Harsh Soni, A.K. Sood, Sriram Ramaswamy Phys. Rev. E 105, 064602 (2022) ; arXiv:2007.04860

  2021

• Inversion of vortex flow around active microalgae under strong confinement, Debasmita Mondal, Ameya G. Prabhune, Sriram Ramaswamy, Prerna Sharma eLife 2021;10:e67663 (arXiv:2003.02040)
• Heating leads to liquid-crystal and crystalline order in a two-temperature active fluid of rods, J Chattopadhyay, S Pannir-Sivajothi, K Varma, S Ramaswamy, C Dasgupta, P K Maiti, Phys. Rev. E 104, 054610 (2021); (arXiv:2105.04571)
• Inertia drives a flocking phase transition in viscous active fluids, R Chatterjee, N Rana, R A Simha, P Perlekar, S Ramaswamy, Phys. Rev. X 11, 031063 (2021); (arXiv:1907.03492)
• Layered chiral active matter: beyond odd elasticity, S J Kole, G P Alexander, S Ramaswamy and A Maitra, Phys Rev Lett 126, 248001 (2021) (Editor’s Suggestion) (arXiv:2012.14321)

  2020

• Phases and excitations of active rod-bead mixtures: simulations and experiments, Harsh Soni, Nitin Kumar, Jyothishraj Nambisan, Rahul Kumar Gupta, A. K. Sood, Sriram Ramaswamy, Soft Matter 16, 7210-7221 (2020) (DOI: 10.1039/C9SM02552A) (arXiv:2001.00173)
• Waves, Algebraic Growth and Clumping in Sedimenting Disk Arrays, R Chajwa, N Menon, S Ramaswamy, R Govindarajan, arXiv:2002.04168, Phys Rev X 10, 041016 (2020)
• Swimmer suspensions on substrates: anomalous stability and long-range order, A Maitra, P Srivastava, M C Marchetti, S Ramaswamy, M Lenz, Phys Rev Lett 124, 028002 (2020) (arXiv:1901.01069)
• Nonmutual torques and the unimportance of motility for long-range order in two-dimensional flocks, L P Dadhichi, J Kethapelli, R Chajwa, S Ramaswamy, A Maitra, Phys Rev E 101, 052601 (2020) (arXiv:1912.06581)
• Omnidirectional transport and navigation of Janus particles through a nematic liquid crystal film D K Sahu, S J Kole, S Ramaswamy, S Dhara Phys. Rev. Research 2, 032009 (2020) (arXiv:1908.11168)

  2019

• Oriented Active Solids, A Maitra, S Ramaswamy, Phys Rev Lett 123, 238001 (2019); (arXiv:1812.01374)
• Active fluids, S Ramaswamy, Nat Rev Phys 1, 640-642 (2019)
• The Matter of Life, Interview by Tom Ireland in The Biologist 66 26-29 (2019)
• Kepler orbits of settling discs, R Chajwa, N Menon, S Ramaswamy, Phys. Rev. Lett. 122, 224501 (2019) (arXiv:1803.10269)
• Trapping and sorting active particles: Motility-induced condensation and smectic defects, N Kumar, R K Gupta, H Soni, S Ramaswamy, A K Sood, Phys. Rev. E 99, 032605 (2019) (arXiv:1803.02278)
• Inferring critical points of ecosystem transitions from spatial data, S Majumder, K Tamma, S Ramaswamy, V Guttal, Ecology 100, e02722 (2019); (bioRxiv:2017/187799)
• Stress Fluctuations in Transient Active Networks, D Goldstein, S Ramaswamy, B Chakraborty, Soft Matter 15, 3520 (2019) (arXiv:1901.08119)
• Pairing, waltzing and scattering of chemotactic active colloids, S Saha, S Ramaswamy, R Golestanian, New J. Phys. 21 063006 (2019) (arXiv:1901.02485),

  2018

• Origins and diagnostics of the nonequilibrium character of active systems, L P Dadhichi, A Maitra, S Ramaswamy, J Stat Mech (2018) 123201 (arXiv:1808.08997)
• Defect unbinding in active nematics, S Shankar, S Ramaswamy, M C Marchetti, M J Bowick, Phys Rev Lett 121, 108002 (2018) (arXiv:1804.06350)
• The low noise phase of a 2d active nematic, S Shankar, S Ramaswamy, M C Marchetti (arXiv:1710.05400) Phys. Rev. E 97, 012707 (2018)
• A nonequilibrium force can stabilize 2D active nematics, A Maitra, P Srivastava, M C Marchetti, J Lintuvuori, S Ramaswamy, and M Lenz, PNAS 115 6934-6939 (2018) (arXiv:1711.02407)

  2017

• Active Matter, S Ramaswamy, J. Stat. Mech. (2017) 054002 (arxiv.org/1705.06269)
• Hydrodynamic instabilities in active cholesteric liquid crystals C A Whitfield, T C Adhyapak, A Tiribocchi, G P Alexander, D Marenduzzo, and S Ramaswamy, Eur Phys Jour E 40 (2017) 50 (arxiv.org/1701.05022)

  2016

• Asymmetric exchange in flocks, L P Dadhichi, R Chajwa, A Maitra and S. Ramaswamy, arXiv:1605.00981
• Sorting motile rods by activity, N Kumar, H Soni, R K Gupta, S Ramaswamy, A.K. Sood, arXiv:1603.08535
• The glass susceptibility: growth kinetics and saturation under shear, S K Nandi, S Ramaswamy, Phys. Rev. E 94, 012607 (2016); arXiv:1309.2389

  2015

• Silent Flocks, Andrea Cavagna, Irene Giardina, Tomas S. Grigera, Asja Jelic, Dov Levine, Sriram Ramaswamy, Massimiliano Viale, Phys Rev Lett 114, 218101 (2015); arXiv:1410.2868; Editor’s Choice and highlighted with a Synopsis in Physics http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.114.218101
• Anisotropic Isometric Fluctuation Relations in experiment and theory on a self- propelled rod, Nitin Kumar, Harsh Soni, Sriram Ramaswamy, and A.K. Sood, Phys. Rev. E 91, 030102 (R) (2015); arXiv:1502.04466
• Active Viscoelastic Matter: from Bacterial Drag Reduction to Turbulent Solids, E. J. Hemingway, A. Maitra, S. Banerjee, M. C. Marchetti, S. Ramaswamy, S. M. Fielding, M. E. Cates, Phys Rev Lett 114, 098302 (2015); arXiv:1410.6077

  2014

• Flocking at a distance in active granular matter, Nitin Kumar, Harsh Soni, Sriram Ramaswamy and A.K. Sood, Nature Communications 5: 4688 doi:10.1038/ncomms5688 (2014); arXiv:1402.4262v2; highlighted in http://tinyurl.com/m3quo2f, http://tinyurl.com/l46stfj, http://tinyurl.com/l6zmzt8 http://tinyurl.com/mjcl862
• Universal power law in crossover from integrability to quantum chaos, R Modak, S Mukerjee, S Ramaswamy, Phys. Rev. B 90 (2014) 075152; arXiv:1309.1865.
• Aspects of the density field in an active nematic, S Mishra, S Puri and S Ra- maswamy, Phil. Trans. R. Soc. A 372: 20130364 (2014); http://dx.doi.org/10.1098/rsta.2013.0364
• Activating membranes, A Maitra, P Srivastava, M Rao and S Ramaswamy, Phys Rev Lett 112 (2014) 258101; arXiv:1311.5055.
• Clusters, asters and collective oscillations in chemotactic colloids, S Saha, R Golestanian, S Ramaswamy, Phys Rev E 89 (2014) 062316; arXiv:1309.4947.
• Nonequilibrium noise in electrophoresis: the microion wind, Suropriya Saha, S Ramaswamy, Phys Rev E 89 (2014) 032307
• Actomyosin contractility rotates the cell nucleus, A Kumar, A Maitra, M Sumit, S Ramaswamy, G V Shivashankar, Sci. Rep. 4, 3781; DOI:10.1038/srep03781 (2014); arXiv:1302.6052

  2013

• Phase-Synchronized State of Oriented Active Fluids, S. Fürthauer and S. Ra- maswamy, arXiv:1307.5705, Phys Rev Lett 111 (2013) 238102
• Mesoscopic theory for fluctuating active nematics, E Bertin, H Chaté, F Ginelli, S Mishra, A Peshkov, S Ramaswamy, New J. Phys. 15 (2013) 085032; arXiv:1305.0772
• The actin cortex as an active wetting layer, J.-F. Joanny, K. Kruse, J. Prost, S. Ramaswamy, arXiv:1302.5025, Eur. Phys. J. E 36 (2013) 52
• Yielding and large deviations in micellar gels: a model, S K Nandi, B Chakraborty, A K Sood and S Ramaswamy, J. Stat. Mech. (2013) P02027; arXiv:1210.1987
• Live Soap: Order, Fluctuations and Instabilities in Active Smectics, T.C. Adhya- pak, S. Ramaswamy, and John Toner, http://arxiv.org/abs/1204.2708, Phys. Rev. Lett. 110 (2013) 118102
• Hydrodynamics of Soft Active Matter, M. C. Marchetti, J.-F. Joanny, S. Ramaswamy, T. B. Liverpool, J. Prost, M. Rao, R.A. Simha, (arxiv.org/1207.2929) Rev. Mod. Phys. 85 (2013) 1143-1189

  2012

• Theory of the domain growth of glassy correlations, S.K. Nandi, S. Ramaswamy (arxiv.org/1205.1152) Phys Rev Lett, 109 (2012) 115702
• Oscillatory settling in wormlike-micelle solutions: bursts and a long time scale, N. Kumar, S. Majumdar, A. Sood, R. Govindarajan, S. Ramaswamy and A.K. Sood, Soft Matter 8 (2012) 4310 (Hot Article) (arxiv.org/1203.2130)
• A drop of active matter, J.-F. Joanny and S. Ramaswamy, J. Fluid Mech. (http://dx.doi.org/10.1017/jfm.2012.131) (arxiv.org/1201.2794)

  2011

• Mode-coupling glass transition in a fluid confined by a periodic potential, S.K. Nandi, S.M. Bhattacharyya, S. Ramaswamy, Phys. Rev. E 84 (2011) 061501 (arxiv.org/abs/1111.0155)
• Symmetry Properties of the Large-Deviation Function of the Velocity of a Self-Propelled Polar Particle, Nitin Kumar, Sriram Ramaswamy, and A. K. Sood, Phys. Rev. Lett. 106 (2011) 118001 (Editor's Suggestion)

  2010

• The Mechanics and Statistics of Active Matter, S Ramaswamy, Annu. Rev. Condens. Matt. Phys. 1 (2010) 323-345 (Inaugural Issue) (arxiv.org/1004.1933)
• A Dynamic Renormalization Group Study of Active Nematics, S Mishra, R A Simha, S Ramaswamy (J. Stat. Mech.(2010) P02003) (arxiv.org/0912.2283)
• Nonequilibrium noise in electrophoresis: the microion wind, S Saha, S Ramaswamy (arxiv.org/0907.0469)

2009

• Dynamics of a stiff biopolymer in an actively contractile background: buckling, stiffening and negative dissipation, N Kikuchi, A Ehrlicher, D Koch, J A Kaes, S Ramaswamy, M Rao [PNAS 106 (2009) 19776-19779] (arxiv.org/0901.4126)
• Universality Class of the Reversible-Irreversible Transition in Sheared Suspensions, G I Menon, S Ramaswamy, Phys Rev E 79 (2009) 061108 (arxiv.org/0801.3881)
• Instabilities and waves in thin films of living fluids, Sumithra Sankararaman and Sriram Ramaswamy, Phys Rev Lett 102 (2009) 118107 (arxiv.org/0809.4918)

2008

• Exact solution of a Brownian inchworm model for self-propulsion, A. Baule, K. Vijay Kumar and S. Ramaswamy, J. Stat. Mech. (2008) P11008 (arxiv.org/0903.1572)
• Active elastic dimers: self-propulsion and current reversal on a featureless track, K. Vijay Kumar, S. Ramaswamy and M. Rao, Phys Rev E (Rapid Comm.) 77 (2008) 020102 R (arxiv.org/0708.1802)

2007

• Active-filament hydrodynamics: instabilities, boundary conditions and rheology, S. Ramaswamy and M. Rao, New Journal of Physics 9 (2007) 423 (Focus Issue on Physics of the Cytoskeleton).
• Perspectives on the mode-coupling approximation for the dynamics of interacting Brownian particles, A. Basu and S. Ramaswamy, J. Stat. Mech. (2007) P11003.
• Long-lived giant number fluctuations in a swarming granular nematic, V. Narayan, S. Ramaswamy, N. Menon, Science 317 (2007) 105 [see Perspective: M van Hecke, Science 317 (2007) 49]; (cond-mat/0612020)
• Shear-flow-induced isotropic to nematic transition in a suspension of active filaments, S. Muhuri, M. Rao and S. Ramaswamy, Europhys Lett 78 (2007) 48002; (cond-mat/0610025)
• Superdiffusion of concentration in wormlike-micelle solutions, Rajesh Ganapathy, A.K. Sood, and Sriram Ramaswamy, Europhys Lett 77 (2007) 18007.

2006

• Active nematics are intrinsically phase-separated, Shradha Mishra and Sriram Ramaswamy, Phys Rev Lett 97 (2006) 090602 (cond-mat/0603051)
• Brownian-drag induced particle current in a model colloidal system, Moumita Das, Sriram Ramaswamy, A.K. Sood, and G. Ananthakrishna, Phys. Rev. E 73 (2006) 061409
• Do current-density nonlinearities cut off the glass transition? M. E. Cates and S. Ramaswamy, Phys. Rev. Lett. 96 (2006) 135701 (cond-mat/0511260)
• Vijay Narayan, Narayanan Menon and Sriram Ramaswamy, Nonequilibrium steady states in a vibrated-rod monolayer: tetratic, nematic and smectic correlations, J. Stat. Mech. (2006) P01005. (cond-mat/0510082)
• The mechanics of active matter: Broken-symmetry hydrodynamics of motile particles and granular layers, S. Ramaswamy and R.A. Simha, Solid State Communications 139 (2006) 617-622
• Rheological chaos in wormlike micelles and nematic hydrodynamics Moumita Das, Ranjini Bandyopadhyay, Buddhapriya Chakrabarti, Chandan Dasgupta, Sriram Ramaswamy and Ajay Sood, in Molecular Gels: Materials with Self-Assembled Fibrillar Networks, Richard G. Weiss and Pierre Terech (editors), Kluwer, Amsterdam (2006).

2005

• Hydrodynamics and phases of flocks, J. Toner, Y. Tu and S. Ramaswamy, Ann. Phys. 318 (2005) 170
• Routes to spatiotemporal chaos in the rheology of nematogenic fluids B. Chakrabarti, M. Das, C. Dasgupta, S. Ramaswamy, A.K. Sood Phys. Rev. E 71 (2005) 021707 (cond-mat/0408282)

  2004

• Spatiotemporal rheochaos in nematic hydrodynamics B. Chakrabarti, M. Das, C. Dasgupta, S. Ramaswamy, A.K. Sood Phys Rev Lett 92 (2004) 055501 (cond-mat/0311101)
• Rheology of active-particle suspensions, Y. Hatwalne, S. Ramaswamy, M. Rao and R. A. Simha, Phys Rev Lett 92 (2004) 118101 (cond-mat/0308529)
• Flow-induced current and voltage generation in carbon nanotubes, S. Ghosh, A.K. Sood, S. Ramaswamy, N. Kumar, Phys. Rev. B 70 (2004) 205423 (cond-mat/0407803)

  2003

• The segregation instability of a sheared suspension film, R. Govindarajan, P.R. Nott and S. Ramaswamy, submitted to Phys. Fluids (2003) (cond-mat/0312189)
• Rheology of disordered lamellar phases, S. Sukumaran, S. Ramaswamy, P.R. Nott and V. Kumaran, submitted to Phys Rev Lett (2003).
• Collective stochastic resonance in shear-induced melting of sliding bilayers M. Das, G. Ananthakrishna and S. Ramaswamy, Phys. Rev. E 68, 061402 (2003) (cond-mat/0307519)
• Active nematics on a substrate: giant number fluctuations and long-time tails, S. Ramaswamy, R.A. Simha and J. Toner, Europhys.Lett. 62 (2003) 196-202 (cond-mat/0208573)

  2002

• Melting-freezing cycles in a relatively sheared pair of crystalline monolayers, M. Das, S. Ramaswamy and G. Ananthakrishna, Europhys Lett 60 (2002) 636-642 (cond-mat/0205030)
• Ratchet for energy transport between identical reservoirs, S. Das, O. Narayan and S. Ramaswamy, Phys Rev E (Rapid Comm) 66, 050103 (2002) (cond-mat/0206372)
• Anomalous heat conduction in one dimensional momentum-conserving systems, O. Narayan and S. Ramaswamy, Phys Rev Lett 89 (2002) 200601 (cond-mat/0205295) [highlighted in R Livi and S Lepri, Nature (News and Views) 421 (2003) 327]
• Driven Heisenberg Magnets: Nonequilibrium Criticality, Spatiotemporal Chaos and Control, J. Das, M. Rao and S. Ramaswamy, Europhys. Lett., 60 (2002) 418-424 (cond-mat/0104566)
• Stripes in sheared non-brownian suspensions with a free surface, R. Govindarajan, P.R. Nott and S. Ramaswamy, Proc. Statphys Kolkata 2002 (Physica A, in press).
• Phase Diagram of a Two-Species Lattice Model with a Linear Instability, S. Ramaswamy, M. Barma, D. Das, and A. Basu (Proc. Discussion Meeting on Slow Dynamics and Freezing, Jawaharlal Nehru University), Phase Transitions B 75 (2002) 363-375
• Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles, R. A. Simha and S. Ramaswamy Phys Rev Lett 89 (2002) 058101 (pdf file of paper)
• Statistical hydrodynamics of ordered suspensions of self-propelled particles: waves, giant number fluctuations and instabilities, R.A. Simha and S. Ramaswamy (Proc. STATPHYS21) Physica A 306 (2002) 262-269 (pdf file of paper)

  2001

• Theory of Suspension Segregation in Partially Filled Horizontal Rotating Cylinders, R. Govindarajan, P.R. Nott and Sriram Ramaswamy, Phys. Fluids (Lett.) 13 (2001) 3517-3520 (pdf file of paper) (cond-mat/0109428)
• The physics of active membranes, S. Ramaswamy and Madan Rao, C.R. Acad. Sci. Paris (special issue on Physics at the Scale of the Cell) t. 2, Ser. IV, 817-839 (2001).
• Issues in the statistical mechanics of steady sedimentation, S. Ramaswamy, Adv. Phys. 50 (2001) 297-341. (pdf file of paper)
• Weak and strong dynamic scaling in a one-dimensional driven coupled-field model: Effects of kinematic waves, D. Das, A. Basu, M. Barma and S. Ramaswamy, Phys. Rev. E 64 (2001) 021402 (pdf file of paper)
• Active Membrane Fluctuations Studied by Micropipet Aspiration, J-B. Manneville, P. Bassereau, S. Ramaswamy, J. Prost, Phys. Rev. E 64 (2001) 021908 (pdf file of paper)

  2000

• Nonequilibrium noise, steady states, and instabilities in membranes with active proteins
  S. Ramaswamy, J. Toner, and J. Prost, Phys. Rev. Lett. 84 (2000) 3494-3497 (pdf file of paper)
• Strong phase separation in a model for sedimenting lattices
  R. Lahiri, M. Barma, and S. Ramaswamy
  Phys. Rev. E 61 (2000) 1648 (pdf file of paper)
• Inequivalence of ensembles in a driven diffusive system
  M. Acharyya, A. Basu, R. Pandit, and S. Ramaswamy
  Phys. Rev. E 61 (2000) 1139 (pdf file of paper)

  1999

• Travelling waves in a drifting flux lattice
  R. Aditi Simha and S. Ramaswamy
  Phys. Rev. Lett 83 (1999) 3285 (pdf file of paper)
• Structure and rheology of the defect-gel states of pure and particle-dispersed lyotropic lamellar phases,
  G. Basappa, Suneel, V. Kumaran, P.R. Nott, S. Ramaswamy, V.M. Naik and D. Rout
  Eur. Phys. Jour. B 12 (1999) 269-276. (pdf file of paper)
• Mean magnetic field and noise cross-correlation in magnetohydrodynamic turbulence: results from a one-dimensional model,
  A. Basu, J.K. Bhattacharjee and S. Ramaswamy,
  Eur. Phys. Jour. B 9 (1999) 725-730 (pdf file of paper)

  1998

• Screened and unscreened phases in sedimenting suspensions,
  A. Levine, S. Ramaswamy, E. Frey and R. Bruinsma,
  Phys. Rev. Lett. 81, 5944-5947 (1998) (pdf file of paper)

  1997

• (i) Self-diffusion of colloids at freezing;
  (ii) Shear-enhanced diffusion in colloids;
  (iii) Excess dissipation in dense emulsions;
  three chapters in Theoretical Challenges in the Dynamics of Complex Fluids
  (lectures in a NATO Advanced Study Institute), Ed. T C B McLeish, Kluwer 1997 (three .ps files tarred into a single file)
• Are steadily moving crystals unstable? R. Lahiri and S. Ramaswamy, Phys. Rev. Lett. 79, 1150-1153 (1997) (pdf file of paper)